Astb Can You Pass This Mechanical Comprehension Test

1. The figure above represents a pipe through which water is flowing in the direction of the arrow. There is a constriction in the pipe at the point indicated by the number 2. Water is being pumped into the pipe at a constant rate of 350 gallons per minute. Of the following, the most accurate statement is that

D. the pressure of the water at point 2 is higher than the pressure at point 1.

A. the velocity of the water at point 2 is the same as the velocity of the water at point 3.

Answer is C. The volume of water flowing at points 1, 2, and 3 must be the same because of the conservation of mass: mass in = mass out. Also, since no water is added or removed after point 1, there cannot be any change of volume.

B. a greater volume of water is flowing past point 1 in a minute than is flowing past point 2.

The volume of water flowing at points 1, 2, and 3 must be the same because of the conservation of mass: mass in = mass out. Also, since no water is added or removed after point 1, there cannot be any change of volume.

Explanation

The volume of water flowing at points 1, 2, and 3 must be the same because of the conservation of mass: mass in = mass out. Also, since no water is added or removed after point 1, there cannot be any change of volume.

2. If nut A is removed from the balanced arm in the figure above, in which direction should nut C be moved to rebalance the arm?

Answer is A. If nut A were removed, it would be necessary to move nut C to the right to counterbalance the loss of the weight of nut A

C. B up.

B. C toward the left.

D. B down.

If nut A were removed, it would be necessary to move nut C to the right to counterbalance the loss of the weight of nut A.

Explanation

If nut A were removed, it would be necessary to move nut C to the right to counterbalance the loss of the weight of nut A.

3. In the figure shown above, one complete revolution of the sprocket wheel will bring weight W2 higher than weight W1 by

D. 60 inches.

Answer is C. The circumference of the wheel is 24 inches. One complete revolution will raise W2 24 inches and lower W1 24 inches, a difference of 48 inches.

A. 24 inches.

B. 36 inches.

The circumference of the wheel is 24 inches. One complete revolution will raise W2 24 inches and lower W1 24 inches, a difference of 48 inches.

Explanation

The circumference of the wheel is 24 inches. One complete revolution will raise W2 24 inches and lower W1 24 inches, a difference of 48 inches.

4. At which point was the basketball moving slowest?

D

B

Answer is C. The vertical component of the momentum of the ball is zero only at position C.

A

The vertical component of the momentum of the ball is zero only at position C, indicating the ball's movement is slowest at that point.

Explanation

The vertical component of the momentum of the ball is zero only at position C, indicating the ball's movement is slowest at that point.

5. If pulley D is the driver in the arrangement of pulleys shown above, the pulley that turns slowest is

D

C

B

Answer is A. Pulley A has the largest circumference. In the arrangement shown, pulley A turns slowest.

Pulley A has the largest circumference. In the arrangement shown, pulley A turns slowest.

Explanation

Pulley A has the largest circumference. In the arrangement shown, pulley A turns slowest.

6. A 150-pound person jumps off a 600-pound raft to a point in the water 10 feet away. Theoretically, the raft would move in the opposite direction a distance of

B. 3 feet

D. 1 foot

C. 5 feet

Answer is A. Let x = theoretical distance moved in the opposite direction.
10 * 150= x * 600
600x= 1500
x= 1500/600
x= 2.5

The correct answer is A. Let x = theoretical distance moved in the opposite direction. 10 * 150 = x * 600. Solving for x gives x = 2.5, hence the raft would move 2.5 feet in the opposite direction.

Explanation

The correct answer is A. Let x = theoretical distance moved in the opposite direction. 10 * 150 = x * 600. Solving for x gives x = 2.5, hence the raft would move 2.5 feet in the opposite direction.

7. If cam A makes 120 complete turns per minute, the setscrew will hit the contact point

C. four times each second.

A. once each second.

Answer is B. Note that with each complete turn of the cam, the setscrew will hit the contact point once

D. three times each second.

The correct answer is b because with each complete turn of the cam, the setscrew will hit the contact point once. Since cam A makes 120 complete turns per minute, it will hit the contact point 120 times in a minute. Therefore, in a second, it will hit the contact point twice (120 divided by 60 seconds).

Explanation

The correct answer is b because with each complete turn of the cam, the setscrew will hit the contact point once. Since cam A makes 120 complete turns per minute, it will hit the contact point 120 times in a minute. Therefore, in a second, it will hit the contact point twice (120 divided by 60 seconds).

8. As shown in the figure above, four air reservoirs have been filled with air by the air compressor. If the main gauge reads 150 pounds, then the tank air gauge will read

Answer is C. The pressure is uniform in the system given. If the main line air gauge reads 150 pounds, the tank air gauge will also read 150 pounds.

D. 100 pounds.

A. 50 pounds.

B. 75 pounds.

The pressure is uniform in the system given. If the main line air gauge reads 150 pounds, the tank air gauge will also read 150 pounds.

Explanation

The pressure is uniform in the system given. If the main line air gauge reads 150 pounds, the tank air gauge will also read 150 pounds.

9. Which of the angles is braced most securely?

D

A

B

Answer is C. As brace C has the greatest area support, it is the most secure.

10. The amount of gas in the balloons is equal. The atmospheric pressure outside the balloons is lowest on which balloon?

B

D

Answer is C. The greater the pressure outside the balloon, the less expansion within the balloon; the less pressure, the greater the expansion.

A

The greater the pressure outside the balloon, the less expansion within the balloon; the less pressure, the greater the expansion.

Explanation

The greater the pressure outside the balloon, the less expansion within the balloon; the less pressure, the greater the expansion.

11. In the figure shown above, X is the driver gear and Y is the driven gear. If the idler gear is rotating clockwise,

Answer is B. When two external gears mesh, they rotate in opposite directions. To avoid this, an idler gear is put between the driver gear and the driven gear.

D. gear X and gear Y are stationary.

A. gear X and gear Y are rotating clockwise.

C. gear X is rotating clockwise, while gear Y is rotating counterclockwise.

When two external gears mesh, they rotate in opposite directions. To avoid this, an idler gear is put between the driver gear and the driven gear.

Explanation

When two external gears mesh, they rotate in opposite directions. To avoid this, an idler gear is put between the driver gear and the driven gear.

12. The figure shown above represents a water tank containing water. The number 1 indicates an intake pipe and 2 indicates a discharge pipe. Which of the following statements is correct?

Answer is C. The tank would overflow only if water flows through the intake pipe at a faster, not slower, rate. The water in the tank would remain at a constant level if rate of intake is equal to rate of discharge. The tank cannot empty completely, as the discharge pipe is not located at the tank's bottom.

A. The tank will eventually overflow if water flows through the intake pipe at a slower rate than it flows out through the discharge pipe.

B. The tank will empty completely if the intake pipe is closed and the discharge pipe is allowed to remain open.

D. The tank will never fill up completely if the intake pipe is partially closed and the discharge pipe is fully open.

The tank would overflow only if water flows through the intake pipe at a faster, not slower, rate. The water in the tank would remain at a constant level if rate of intake is equal to rate of discharge. The tank cannot empty completely, as the discharge pipe is not located at the tank's bottom.

Explanation

The tank would overflow only if water flows through the intake pipe at a faster, not slower, rate. The water in the tank would remain at a constant level if rate of intake is equal to rate of discharge. The tank cannot empty completely, as the discharge pipe is not located at the tank's bottom.

13. If the float in the tank develops a bad leak, what will happen?

B. The float will stay in the position shown.

A. The flow of fuel will stop.

D. The engine will start running smoothly.

Answer is C. If the float in the tank develops a bad leak, it will fill with water and submerge. This will elevate the needle valve causing it to remain in an open position.

If the float in the tank develops a bad leak, it will fill with water and submerge. This will elevate the needle valve causing it to remain in an open position.

Explanation

If the float in the tank develops a bad leak, it will fill with water and submerge. This will elevate the needle valve causing it to remain in an open position.

14. What is the maximum weight that can be lifted with a 100-pound pull when the mechanical advantage is 2?

D. 400 pounds.

C. 300 pounds.

Answer is B. The number of parts of the rope going to and from the movable block indicates a mechanical advantage of 2. Accordingly, a 100-lb. pull can lift, theoretically, a 200-lb. weight.

A. 100 pounds.

The number of parts of the rope going to and from the movable block indicates a mechanical advantage of 2. Accordingly, a 100-lb. pull can lift, theoretically, a 200-lb. weight.

Explanation

The number of parts of the rope going to and from the movable block indicates a mechanical advantage of 2. Accordingly, a 100-lb. pull can lift, theoretically, a 200-lb. weight.

15. One revolution of the worm gear will turn the sector gear through an angle of

A. 5 degrees.

D. 20 degrees.

C. 15 degrees.

Answer is B. Note that 2 revolutions of the worm gear will turn the sector gear 20 degrees. Accordingly, one revolution of the worm gear will turn the sector gear through an angle of 10 degrees

Note that 2 revolutions of the worm gear will turn the sector gear 20 degrees. Accordingly, one revolution of the worm gear will turn the sector gear through an angle of 10 degrees.

Explanation

Note that 2 revolutions of the worm gear will turn the sector gear 20 degrees. Accordingly, one revolution of the worm gear will turn the sector gear through an angle of 10 degrees.

16. A pry bar is used to move a concrete block. A force of 80 lbs. applied as shown will produce a tipping force on the edge of the block of

B. 240 lbs.

Answer is C. Let x equal the tipping force produced on the edge of the block.
80*4= 1 * x
320= x

A. 80 lbs.

D. 400 lbs.

Let the tipping force produced on the edge of the block be represented by x. By applying the principle of moments, the equation becomes 80 * 4 = 1 * x, which simplifies to 320 = x. Hence, the correct tipping force is 320 lbs.

Explanation

Let the tipping force produced on the edge of the block be represented by x. By applying the principle of moments, the equation becomes 80 * 4 = 1 * x, which simplifies to 320 = x. Hence, the correct tipping force is 320 lbs.

17. If the contacts come together once every second, the cam is rotating at

C. 60 rpm.

Answer is A. Note that with each complete turn of the cam, the contacts come together twice. If the contacts come together 60 times a minute, the cam must be rotating at 30 rpm.

D. 15 rpm.

B. 45 rpm.

18. One complete turn of the drum crank will move the weight vertically upward a distance of

D. 4 feet

Answer is C. One complete turn of the drum crank will raise the rope 2′ on the 2′ portion of the drum and 1′ on the 1′ portion of the drum. The net result is vertical movement upward a distance of

B. 2 feet

A. 1 foot

One complete turn of the drum crank will raise the rope 2' on the 2' portion of the drum and 1' on the 1' portion of the drum. The net result is vertical movement upward a distance of 3 feet.

Explanation

One complete turn of the drum crank will raise the rope 2' on the 2' portion of the drum and 1' on the 1' portion of the drum. The net result is vertical movement upward a distance of 3 feet.

19. A weight is to be raised by means of the rope attached to the truck. If the truck moves forward 30 feet, then the weight will rise

A. 20 feet.

C. 10 feet.

D. 25 feet.

Answer is B. The TMA of the pulley system is 2.

The TMA of the pulley system is 2, so the weight will rise half the distance the truck moves forward.

Explanation

The TMA of the pulley system is 2, so the weight will rise half the distance the truck moves forward.

20. The block and tackle shown has two pulleys of equal diameter. While the weight is being raised, pulley 2 will rotate at

B. the same speed as pulley 1.

C. one-half the speed of pulley 1.

D. three times the speed of pulley 1.

Answer is A. Pulley 2 is a fixed pulley; pulley 1 is a movable one. Both are of equal diameter. If the rope is pulled a distance equal to the circumference of pulley 2 (one full turn), pulley 1 would move up only half that distance making only a half turn.

Pulley 2 is a fixed pulley; pulley 1 is a movable one. Both are of equal diameter. If the rope is pulled a distance equal to the circumference of pulley 2 (one full turn), pulley 1 would move up only half that distance making only a half turn.

Explanation

Pulley 2 is a fixed pulley; pulley 1 is a movable one. Both are of equal diameter. If the rope is pulled a distance equal to the circumference of pulley 2 (one full turn), pulley 1 would move up only half that distance making only a half turn.

21. In order to open the valve twice every second, with 10 projection rods on the wheel, the wheel must rotate at

A. 6 rpm.

Answer is C. Twice per second = 120 times a minute.

With 10 projection rods on the wheel, the wheel must rotate at 12 rpm to make 120 rod contacts per minute.

B. 9 rpm.

D. 15 rpm.

Twice per second = 120 times a minute. With 10 projection rods, 120 contacts per minute require 12 rpm rotation.

Explanation

Twice per second = 120 times a minute. With 10 projection rods, 120 contacts per minute require 12 rpm rotation.

22. With the wheels in the position shown, which wheel will rotate faster?

D. It is impossible to determine which wheel will rotate faster based on the information provided.

B. wheels S and T will rotate at the same speed.

A. wheel S will rotate at a faster speed than wheel T.

Answer is C. Both wheels S and T have the same diameter. However, the driver wheel makes contact with wheel T close to its center and makes contact with wheel S very near its edge. Accordingly, wheel T will rotate at a much faster speed than wheel S.

Both wheels S and T have the same diameter. However, the driver wheel makes contact with wheel T close to its center and makes contact with wheel S very near its edge. Accordingly, wheel T will rotate at a much faster speed than wheel S.

Explanation

Both wheels S and T have the same diameter. However, the driver wheel makes contact with wheel T close to its center and makes contact with wheel S very near its edge. Accordingly, wheel T will rotate at a much faster speed than wheel S.

23. The figure above shows a crank and piston. The piston moves from mid-position to the extreme left and then back to the mid-position if the crank makes a

C. 1/2 turn is needed to get to the extreme left position and another 1/2 turn is required to return to the mid-position.

D. 1/4 turn is needed to get to the extreme left position and another 1/4 turn is required to return to the mid-position.

A. A turn is needed to get to the extreme right position and another turn is required to return to the mid-position.

Answer is B. A turn is needed to get to the extreme left position and another turn is required to return to the mid-position.

The crank starts at the mid-position and moves a full turn to get the piston to the extreme left position, it then takes another full turn to return to the mid-position.

Explanation

The crank starts at the mid-position and moves a full turn to get the piston to the extreme left position, it then takes another full turn to return to the mid-position.

24. The figure above shows a lever-type safety valve. It will blow off at a higher pressure if weight W is

B. moved to the left.

D. kept in the same position.

A. decreased.

Answer is C. By increasing the length of the level arm, the effort is increased enabling the valve to blow off at a higher pressure.

By increasing the length of the level arm, the effort is increased enabling the valve to blow off at a higher pressure.

Explanation

By increasing the length of the level arm, the effort is increased enabling the valve to blow off at a higher pressure.

25. In the figure above, all four springs are identical. In Case 1, with the springs end to end, the stretch of each spring due to the 5-pound weight is

A. as much as in Case 2.

Answer is C. In case 2, each spring is supporting pounds ( of 5 pounds) and would extend a certain distance. In case 1, each spring is supporting 5 pounds (the full weight) and would extend twice the distance of that for case 2.

D. half as much as in Case 2.

B. the same as in Case 2.

In case 2, each spring is supporting 1/4 pounds (1/4 of 5 pounds) and would extend a certain distance. In case 1, each spring is supporting 5 pounds (the full weight) and would extend twice the distance of that for case 2.

Explanation

In case 2, each spring is supporting 1/4 pounds (1/4 of 5 pounds) and would extend a certain distance. In case 1, each spring is supporting 5 pounds (the full weight) and would extend twice the distance of that for case 2.

26. In the figure above, the micrometer reads

B. .2250

C. .2120

Answer is A. The reading is obtained as follows:

.2 (on the sleeve scale)
.025 (on the sleeve scale)
(on the thimble scale)

D. .2300

The reading is obtained by adding the values on the sleeve scale, which is .2 and .025, then adding the value on the thimble scale, which is .0025. This gives a total reading of .2270

Explanation

The reading is obtained by adding the values on the sleeve scale, which is .2 and .025, then adding the value on the thimble scale, which is .0025. This gives a total reading of .2270

27. In the figure above, the threaded block can slide in the slot but cannot revolve. If the hand wheel is turned 20 revolutions clockwise, the threaded block will move

B. 1 inch to the left.

Answer is C. The hand wheel tightens to the left when rotated clockwise since it has a right-handed thread. If the hand wheel is turned 20 revolutions, it moves one inch to the left, pulling the threaded block one inch in the opposite direction (to the right).

A. 1 inch to the left.

D. No movement as the hand wheel is turned.

The hand wheel tightens to the left when rotated clockwise since it has a right-handed thread. If the hand wheel is turned 20 revolutions, it moves one inch to the left, pulling the threaded block one inch in the opposite direction (to the right).

Explanation

The hand wheel tightens to the left when rotated clockwise since it has a right-handed thread. If the hand wheel is turned 20 revolutions, it moves one inch to the left, pulling the threaded block one inch in the opposite direction (to the right).

28. If all three switches are closed to the left, which lamps will light up?

B. No. 2 and No. 3 light

D. No lamps light up

Answer is A. If all three switches are closed to the left, the closed circuit would not include Lamp No. 2.

C. Only No. 3 lights

When all three switches are closed to the left, the closed circuit includes Lamp No. 1 and No. 3, but not Lamp No. 2.

Explanation

When all three switches are closed to the left, the closed circuit includes Lamp No. 1 and No. 3, but not Lamp No. 2.

29. If switches No. 1 and No. 2 are closed to the right and switch No. 3 is closed to the left, the following lamp condition results:

Only No. 3 lights

No. 1 and No. 3 light

No lamps light

Answer is B. If switches No. 1 and No. 2 are closed to the right, and switch No. 3 is closed to the left, the closed circuit would not include Lamp No. 1.

When switches 1 and 2 are closed to the right and switch 3 is closed to the left, only Lamp No. 2 and Lamp No. 3 would receive electricity in the closed circuit, so the correct answer is B.

Explanation

When switches 1 and 2 are closed to the right and switch 3 is closed to the left, only Lamp No. 2 and Lamp No. 3 would receive electricity in the closed circuit, so the correct answer is B.