Net Force Quiz - Learn Physics Concepts

1. What is the net force on an object if two equal forces push in opposite directions?

0 N

10 N

20 N

30 N

When two equal forces act in opposite directions, they cancel each other out, resulting in a net force of zero Newtons (0 N). This is a fundamental principle of vector addition where forces in opposite directions subtract from each other. In this case, the equal magnitude and opposite direction mean that the forces balance perfectly, leaving no resultant force to change the object’s state of motion.

Explanation

When two equal forces act in opposite directions, they cancel each other out, resulting in a net force of zero Newtons (0 N). This is a fundamental principle of vector addition where forces in opposite directions subtract from each other. In this case, the equal magnitude and opposite direction mean that the forces balance perfectly, leaving no resultant force to change the object’s state of motion.

2. If three forces, 7 N, 2 N, and 4 N, act on an object in the same direction, what is the net force?

9 N

13 N

11 N

3 N

When three forces act in the same direction, they are simply added together to find the net force. Adding 7 N, 2 N, and 4 N results in a total net force of 7 N + 2 N + 4 N = 13 N. This sum indicates the combined strength of the forces propelling the object in that direction.

Explanation

When three forces act in the same direction, they are simply added together to find the net force. Adding 7 N, 2 N, and 4 N results in a total net force of 7 N + 2 N + 4 N = 13 N. This sum indicates the combined strength of the forces propelling the object in that direction.

3. What is the net force if an object is subjected to 20 N up and 20 N down?

0 N

40 N up

40 N down

20 N

When an object experiences equal forces of 20 N pushing up and 20 N pushing down, these forces directly oppose each other and have equal magnitudes but opposite directions. According to the principles of vector addition in physics, when two equal but opposite forces act on an object, they cancel each other out completely. Therefore, the net force acting on the object is zero Newtons (0 N). This cancellation means that there is no resultant force to alter the object’s state of motion, leading it to either remain at rest or continue moving at a constant velocity if it was already in motion.

Explanation

When an object experiences equal forces of 20 N pushing up and 20 N pushing down, these forces directly oppose each other and have equal magnitudes but opposite directions. According to the principles of vector addition in physics, when two equal but opposite forces act on an object, they cancel each other out completely. Therefore, the net force acting on the object is zero Newtons (0 N). This cancellation means that there is no resultant force to alter the object’s state of motion, leading it to either remain at rest or continue moving at a constant velocity if it was already in motion.

4. An object is pulled with 15 N to the north and 10 N to the south. What is the net force?

5 N north

5 N south

25 N north

25 N south

When calculating forces acting in opposite directions, subtract the smaller from the larger and keep the direction of the larger force. Here, 15 N north and 10 N south result in a net force of 15 N - 10 N = 5 N north. The object will experience a resultant force pushing it northward as the northern force is stronger.

Explanation

When calculating forces acting in opposite directions, subtract the smaller from the larger and keep the direction of the larger force. Here, 15 N north and 10 N south result in a net force of 15 N - 10 N = 5 N north. The object will experience a resultant force pushing it northward as the northern force is stronger.

5. A car has a forward force of 300 N and a frictional force of 250 N acting against it. What is the net force?

50 N forward

50 N backward

550 N forward

550 N backward

The car experiencing a forward force of 300 N and a backward frictional force of 250 N results in a net forward force calculated by 300 N - 250 N = 50 N. This remaining forward force indicates that the car will accelerate forward, as the drive force exceeds the friction resisting it.

Explanation

The car experiencing a forward force of 300 N and a backward frictional force of 250 N results in a net forward force calculated by 300 N - 250 N = 50 N. This remaining forward force indicates that the car will accelerate forward, as the drive force exceeds the friction resisting it.

6. What happens to the motion of an object if the net force on it is zero?

It speeds up.

It slows down.

It changes direction.

It stays the same.

A net force of zero indicates that all forces acting on an object are balanced. There are no unbalanced forces to change the object’s motion, meaning it will maintain its current state of motion. According to Newton's first law of motion, an object at rest stays at rest, and an object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force. Here, with zero net force, the object’s motion remains unchanged.

Explanation

A net force of zero indicates that all forces acting on an object are balanced. There are no unbalanced forces to change the object’s motion, meaning it will maintain its current state of motion. According to Newton's first law of motion, an object at rest stays at rest, and an object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force. Here, with zero net force, the object’s motion remains unchanged.

7. Calculate the net force: 10 N to the left and 4 N to the right.

6 N to the left

6 N to the right

14 N to the left

14 N to the right

To find the net force when 10 N acts to the left and 4 N to the right, subtract the smaller force from the larger force while retaining the direction of the larger force. The calculation is 10 N - 4 N = 6 N. The resulting net force is 6 N to the left, indicating that the leftward force predominates, causing the object to move left.

Explanation

To find the net force when 10 N acts to the left and 4 N to the right, subtract the smaller force from the larger force while retaining the direction of the larger force. The calculation is 10 N - 4 N = 6 N. The resulting net force is 6 N to the left, indicating that the leftward force predominates, causing the object to move left.

8. If a 5 N force and a 3 N force act in the same direction, what is the net force?

2 N

8 N

15 N

5 N

If two forces, 5 N and 3 N, act in the same direction, their magnitudes simply add up. The vector addition here is straightforward: 5 N + 3 N = 8 N. This results in a net force of 8 N in the direction both forces were acting. The cumulative effect of these aligned forces increases the total force exerted on the object, moving it more effectively in their shared direction.

Explanation

If two forces, 5 N and 3 N, act in the same direction, their magnitudes simply add up. The vector addition here is straightforward: 5 N + 3 N = 8 N. This results in a net force of 8 N in the direction both forces were acting. The cumulative effect of these aligned forces increases the total force exerted on the object, moving it more effectively in their shared direction.

9. Three forces act on an object: 5 N left, 10 N right, and 3 N left. What is the net force?

2 N left

2 N right

18 N left

18 N right

Calculating the net force with three forces involves summing up like directions and then finding the difference. Here, 5 N and 3 N left add up to 8 N left, and the single rightward force is 10 N. The net force is calculated by subtracting the total leftward force from the rightward force: 10 N - 8 N = 2 N right. This means the rightward force slightly overcomes the leftward forces, nudging the object right.

Explanation

Calculating the net force with three forces involves summing up like directions and then finding the difference. Here, 5 N and 3 N left add up to 8 N left, and the single rightward force is 10 N. The net force is calculated by subtracting the total leftward force from the rightward force: 10 N - 8 N = 2 N right. This means the rightward force slightly overcomes the leftward forces, nudging the object right.

10. An object has four forces acting on it: 20 N north, 20 N south, 10 N east, and 5 N west. What is the net force?

5 N east

5 N west

10 N east

15 N east

With four forces acting in two dimensions (north-south and east-west), cancel out opposing forces first. 20 N north cancels with 20 N south, and 10 N east partially cancels with 5 N west, leaving a net force of 5 N east. This remaining force means the object will move eastward.

Explanation

With four forces acting in two dimensions (north-south and east-west), cancel out opposing forces first. 20 N north cancels with 20 N south, and 10 N east partially cancels with 5 N west, leaving a net force of 5 N east. This remaining force means the object will move eastward.