The slope of a plot of position versus time for a moving object gives the object’s velocity. The slope of a plot of velocity versus time gives the object’s acceleration.
| 1 | |
| ||
| ||
A honeybee leaves the hive and travels 2 km before returning. Is the displacement for the trip the same as the distance traveled? If not, why not?
| 2 | |
| ||
| ||
Two buses depart from Chicago, one going to New York and one to San Francisco. Each bus travels at a speed of 30 m/s. Do they have equal velocities? Explain.
| 3 | |
| ||
| ||
Is the average speed of a vehicle a vector or a scalar quantity? Provide a reason for your answer.
| 4 | |
| ||
| ||
Often, traffic lights are timed so that if you travel at a certain constant speed, you can avoid all red lights. Discuss how the timing of the lights is determined, considering that the distance between them varies from one light to the next.
| 5 | |
| ||
| ||
One of the following statements is incorrect. (a) The car traveled around the track at a constant velocity. (b) The car traveled around the track at a constant speed. Which statement is incorrect and why?
| 6 | |
| ||
| ||
Give an example from your own experience in which the velocity of an object is zero for just an instant of time, but its acceleration is not zero.
| 7 | |
| ||
| ||
At a given instant of time, a car and a truck are traveling side by side in adjacent lanes of a highway. The car has a greater velocity than the truck. Does the car necessarily have a greater acceleration? Explain.
| 8 | |
| ||
| ||
The average velocity for a trip has a positive value. Is it possible for the instantaneous velocity at any point during the trip to have a negative value? Justify your answer.
| 9 | |
| ||
| ||
A runner runs half the remaining distance to the finish line every ten seconds. She runs in a straight line and does not ever reverse her direction. Does her acceleration have a constant magnitude? Give a reason for your answer.
| 10 | |
| ||
| ||
An object moving with a constant acceleration can certainly slow down. But can an object ever come to a permanent halt if its acceleration truly remains constant? Explain.
| 11 | |
| ||
| ||
Review Concept Simulation 2.2 before answering this question. An experimental vehicle slows down and comes to a halt with an acceleration whose magnitude is 9.80 m/s2. After reversing direction in a negligible amount of time, the vehicle speeds up with an acceleration of 9.80 m/s2. Other than being horizontal, how is this motion different, if at all, from the motion of a ball that is thrown straight upward, comes to a halt, and falls back to earth?
| 12 | |
| ||
| ||
A ball is dropped from rest from the top of a building and strikes the ground with a speed vf. From ground level, a second ball is thrown straight upward at the same instant that the first ball is dropped. The initial speed of the second ball is v0=vf, the same speed with which the first ball will eventually strike the ground. Ignoring air resistance, decide whether the balls cross paths at half the height of the building, above the halfway point, or below the halfway point. Give your reasoning.
| 13 | |
| ||
| ||
Review Concept Simulation 2.3 before answering this question. Two objects are thrown vertically upward, first one, and then, a bit later, the other. Is it possible that both reach the same maximum height at the same instant? Account for your answer.
| 14 | |
| ||
| ||
The muzzle velocity of a gun is the velocity of the bullet when it leaves the barrel. The muzzle velocity of one rifle with a short barrel is greater than the muzzle velocity of another rifle that has a longer barrel. In which rifle is the acceleration of the bullet larger? Explain your reasoning.
|