1.
A basketball is tossed up into the air. What can you say about the top of theÂ trajectory is
Correct Answer
C. Acceleration is - 9.8 m/s/s, Velocity is 0 m/s
Explanation
At the top of the trajectory, the basketball reaches its maximum height and momentarily stops moving vertically. This means that the velocity is 0 m/s. Since the basketball is moving upwards, the acceleration due to gravity acts in the opposite direction, causing a deceleration. Therefore, the acceleration is -9.8 m/s/s.
2.
Â Â Â This graph is a position / time graph.Which ones are moving to the left
Correct Answer
E. E
Explanation
The graph is a position/time graph, which means it shows the position of objects over time. The question asks which objects are moving to the left. Looking at the graph, we can see that object E is the only one with a negative slope, indicating that it is moving in the negative direction of the x-axis, which is to the left. Therefore, the correct answer is E.
3.
A Canadian goose flew 845 km from Southern California to Oregon with an average speed of
30.5 m/s. How long, in hours, did it take the goose to make this journey?Don't forget convert the km to meters.
Correct Answer
E. 7.7 h
Explanation
The Canadian goose flew 845 km, which needs to be converted to meters by multiplying by 1000, resulting in 845,000 meters. The average speed of the goose was 30.5 m/s. To find the time it took for the journey, divide the distance by the speed: 845,000 meters / 30.5 m/s = 27,704.92 seconds. To convert this to hours, divide by 3600 (the number of seconds in an hour): 27,704.92 seconds / 3600 seconds/hour = 7.6958 hours, which rounds to 7.7 hours. Therefore, it took the goose 7.7 hours to make the journey.
4.
A train approaches a small town with a constant velocity of +28.6 m/s. The operator applies the brake, reducing the train’s velocity to +11.4 m/s. If the average acceleration of the train during braking is –1.35 m/s2, for what elapsed time does the operator apply the brake?
Correct Answer
B. 12.74s
Explanation
We can use the formula:
[vf = vi + at]
Where:
- (vf) is the final velocity (11.4 m/s).
- (vi) is the initial velocity (28.6 m/s).
- (a) is the acceleration (-1.35 m/s²).
- (t) is the time.
Now, plug in the values:
[11.4 = 28.6 + (-1.35)t]
Now, solve for (t):
[-1.35t = 11.4 - 28.6]
[-1.35t = -17.2]
[t = {-17.2}/{-1.35} = (approx) 12.74]
So, the operator applies the brake for approximately 12.74 seconds.
5.
Starting from rest, a particle confined to move along a straight line is accelerated at a rate of 5.0 m/s2.
Correct Answer
C. The speed of the particle increases by 5.0 m/s during each second.
Explanation
The correct answer is "The speed of the particle increases by 5.0 m/s during each second." This answer is supported by the statement that the particle is accelerated at a rate of 5.0 m/s2. Acceleration is the rate at which an object's velocity changes, and in this case, the particle's velocity is increasing by 5.0 m/s every second. This means that its speed is increasing by 5.0 m/s every second, which aligns with the given answer.
6.
An object moving along a straight line is decelerating. Which one of the following statements
concerning the objectâ€™s acceleration is necessarily true?
Correct Answer
C. The direction of the acceleration is in the direction opposite to that of the velocity.
Explanation
When an object is decelerating, it means that its velocity is decreasing. Since the direction of the acceleration is always in the same direction as the change in velocity, the acceleration will be in the opposite direction to that of the velocity. Therefore, the statement "The direction of the acceleration is in the direction opposite to that of the velocity" is necessarily true.
7.
The minimum takeoff speed for a certain airplane is 75 m/s. What is the acceleration for
the plane must leave a 950m runway? Assume the plane starts from rest at one end of the
runway.
Correct Answer
B. 3.0 m/s/s
Explanation
Show your work on another paper for me to see. Pass in
8.
A rock is thrown vertically upward from the surface of the earth. The rock rises to some maximum
height and falls back toward the surface of the earth. Which one of the following statements
concerning this situation is true if air resistance is neglected?
Correct Answer
B. The ball is a freely falling body for the duration of its flight.
Explanation
When air resistance is neglected, the only force acting on the rock is gravity. Gravity causes the rock to accelerate downwards, regardless of whether it is rising or falling. This means that the rock is in free fall throughout its entire flight, experiencing the same acceleration due to gravity. Therefore, the statement "The ball is a freely falling body for the duration of its flight" is true.