Solutions: Speed, Velocity, and Acceleration-2
In Brief
This page includes solutions to the set of questions related to the
Speed, Velocity, and Acceleration.
This helps learners to ensure their learning on
aspects of physics in general but also Speed, Velocity, and Acceleration questions mentioned in
the practice quiz section.
It is strongly recommended to do the practice quiz before looking at the provided answers.
Brief about Answers- Part 2
This page includes solutions to the set of questions related to Physics.
IT gives an opportunities to see answers and to assess learners if they grasped the right knowledge on speed, velocity, and acceleration:
This helps to get correct any misconceptions and understand speed, velocity, and acceleration.
Question 1:
A ball is projected upward. Eventually, after the ball reaches its maximum height, it will fall back.
Indicate which statement is correct:
- speed never changes
- At the highest point in its motion, the ball's velocity is zero.
- At the highest point in its motion, the ball's velocity is not zero
- none of the above
Answer:
At the highest point in its motion, the ball's velocity is zero.
Question 2:
Assume a student throws a ball vertically downward with a velocity of 10 m/s.
If air friction is considered negligable then calculate the speed of the ball one second later.
- 9.8 m/s
- 20 m/s
- 19.8 m/s
- 18.8 m/s
Answer: assuming that g = 9.8 m/s2 then speed of the ball 1 second later = 19.8 m/s
Question 3:
Suppose you throw a ball vertically with a velocity of 10 m/s.
Approximately, when will it reach its highest height?
Answer: In 1 s. After 1 second, the gravity will push it down.
Question 4:
Assume a television screen fall down from rest at a great height.
Calculate the speed after it has fallen for 5 seconds where air resistance is considered negligible.
- 49 m/s
- 48 m/s
- 47m/s
- 46m/s
Answer: 49 m/s
Explanation: acceleration (a) = speed (v) divided by elapased time (t), which implies that v = a × t = 9.8 m/s2 × 5 s = 49 m/s
Question 5:
Assume a box of 5 kg is dropped from a building and hits the ground in 7 s.
Calculate the time it takes for a 10-kg box to hit the ground where air resistance is considered negligible.
Answer: 7 s
Explanation: since air resistance is zero then the time would stay the same.
Question 6:
If a rocket is fired from a fighter jet and assuming that air resistance is negligible.
Which statement is correct about the rocket.
- The rocket stops immediately.
- Its speed doubles every second.
- Its speed increases at 9.8 m/s.
- none of the above.
Answer: Its speed increases at 9.8 m/s.
Question 7:
If you throw a ball up in the air.
Indicate the status of the ball when it reaches its highest point.
- acceleration is zero.
- speed doubles every second.
- velocity is halved and the acceleration is downward.
- velocity is zero and the acceleration is downward.
- none of the above.
Answer: velocity is zero and the acceleration is downward.
Question 8:
If you throw a ball up in the air with an initial velocity of 20m/s.
Calculate the ball's velocity after 4 seconds.
- − 19.2 m/s
- 0 m/s
- 19.2 m/s
- 20 m/s
Answer: − 19.2 m/s
Explanation: 20 m/s - 4 s × 9.8 m/s2 = − 19.2 m/s
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