AP physics

You are riding in an enclosed train car moving at 90km/h. If you throw a baseball straight up, where will the baseball land?

In your hand

You are in the middle of a large field. You walk in a straight line for 100 m, then turn left and walk 100 m more in a straight line before stopping. When you stop, you are 100 m from your starting point. How many degrees did you turn?

120

How many sig figs in 0.0078

2

How many sig figs in 1.32+25.2?

3

You drop a rock off a bridge. When the rock has fallen 4 m, you drop a second rock.As the two rocks continue to fall, what happens to their velocities?

Both increase at the same rate.

Two cars emerge side by side from a tunnel. Car A is traveling with a speed of 60 km/h and has an acceleration of 40 km/h/min. Car B has a speed of 40 km/h and has an acceleration of 60 km/h/min. Which car is passing the other as they come out of the tunnel? Explain your reasoning.

Car B beats Car A out of the tunnel because his acceleration is greater. The greater acceleration makes up for the slower velocity.

Which is not true about an order-of-magnitude estimation?

It will always be accurate to at least two significant figures.

Which of the three kicks in the figure is in the air for the longest time ? They all reach the same maximum height h. Ignore air resistance.

Same

A ball is dropped from the top of a tall building. At the same instant, a second ball is thrown upward from the ground level. When the two balls pass one another, one on the way up, the other on the way down, compare the magnitudes of their acceleration:

The acceleration of both balls is the same.

Which statements are not valid for a projectile? Take up as positive

The acceleration of the projectile is positive and decreasing when the projectile is moving upwards, zero at the top, and increasingly negative as the projectile descends. The velocity at the highest point is 0

You travel from point A to point B in a car moving at a constant speed of 70 km/h. Then you travel the same distance from point B to another point C, moving at a constant speed of 90 km/h. Is your average speed for the entire trip from A to C equal to 80 km/h? Explain why or why no

The average speed is the total distance traveled/ total time taken. We know the distance between the points are the same. So 80km/h would not be the average speed because it is the the distance over 70km/h plus average speed/ 90km/h.

A hunter is aiming horizontally at a monkey who is sitting in a tree. The monkey is so terrified when it sees the gun that it falls off the tree. At that very instant, the hunter pulls the trigger.

The bullet will hit the monkey because both the monkey and the bullet are falling downward at the same rate due to gravity.

At time t=0 an object is traveling to the right along the +x axis at a speed of 10.0 m/s with acceleration -2.0 m/ Which statement is true?

The object will slow down, momentarily stopping, then pick up speed moving to the left.

One ball is dropped vertically from a window. At the same instant, a second ball is thrown horizontally from the same window. Which ball has the greater speed at ground level?

The thrown ball.

Can an object be increasing in speed as its acceleration decreases? If so, give an example. If not, explain.

Yes. When you are on a bus at a stop light and stomp on the gas, the bus speeds up. When you take your foot off the gas, you still speed up but the acceleration decreases because you are not gaining speed at the same rate you were when your foot was on the gas.

A bullet is fired from a rifle begins to fall

as soon as it leaves the barrel

Accuracy represents

how close a measurement is to the true value.

A car travels 10 m/s east. Another car travels 10 m/s north. The relative speed of the first car with respect to the second is

less than 20m/s

The magnitude of a component of a vector must be

less than or equal to the magnitude of the vector.

Which of the following statements is true? At the highest point,

the magnitude of the velocity is the slowest.

Ball is thrown straight up. What are the velocity and acceleration of the ball at the highest point in its path?

v=0,a=9.8m/s2down.

In which of the following cases does a car have a negative velocity and a positive acceleration? A car that is traveling in the

−x direction decreasing in speed