Physics Chapter 2

A light-year is the distance that light travels in one year. The speed of light is 3.00 × 10^8 m/s. How many miles are there in one light-year? (1 mi = 1609 m, 1 y = 365 d)

5.88 × 10^12 mi

You drive 6.0 km at 50 km/h and then another 6.0 km at 90 km/h. Your average speed over the 12 km drive will be greater than 70 km/h. equal to 70 km/h. less than 70 km/h. exactly 38 km/h. It cannot be determined from the information given because we must also know directions traveled.

less than 70 km/h.

If the velocity versus time graph of an object is a horizontal line, the object is moving with zero acceleration. moving with constant non-zero acceleration. at rest. moving with increasing speed.

moving with zero acceleration.

Which of the following quantities has units of a displacement? (There could be more than one correct choice.) 32 ft/s2 vertically downward 40 km southwest 9.8 m/s2 -120 m/s 186,000 mi

40 km southwest 186,000 mi

A water rocket can reach a speed of 75 m/s in 0.050 seconds from launch. What is its average acceleration?

1500 m/s^2

A car is traveling at 26.0 m/s when the driver suddenly applies the brakes, causing the car to slow down with constant acceleration. The car comes to a stop in a distance of 120 m. How fast was the car moving when it was 60.0 m past the point where the brakes were applied?

18.4 m/s

Abby throws a ball straight up and times it. She sees that the ball goes by the top of a flagpole after 0.50 s and reaches the level of the top of the pole after a total elapsed time of 4.1 s. What was the speed of the ball at launch? Neglect air resistance.

23 m/s

An object starts from rest and undergoes uniform acceleration. During the first second it travels 5.0 m. How far will it travel during the third second?

25 m

A baseball is hit with a bat and, as a result, its direction is completely reversed and its speed is doubled. If the actual contact with the bat lasts 0.45 s, what is the ratio of the magnitude of the average acceleration of the ball to its original speed? 6.7 s-1 4.4 s-1 2.2 s-1 0.15 s-1

6.7 s^-1

A cart with an initial velocity of 5.0 m/s to the right experiences a constant acceleration of 2.0 m/s^2 to the right. What is the cart's displacement during the first 6.0 s of this motion?

66 m

A ball is thrown upward at a velocity of 19.6 m/s. What is its velocity after 3.0 s, assuming negligible air resistance?

9.8 m/s downward

Which of the following situations is impossible? An object has velocity directed east and acceleration directed west. An object has velocity directed east and acceleration directed east. An object has zero velocity but non-zero acceleration. An object has constant non-zero acceleration and changing velocity. An object has constant non-zero velocity and changing acceleration.

An object has constant non-zero velocity and changing acceleration.

Human reaction time is usually greater than 0.10 s. If your friend holds a ruler between your fingers and releases it without warning, how far can you expect the ruler to fall before you catch it, assuming negligible air resistance? At least 3.0 cm At least 4.9 cm At least 6.8 cm At least 9.8 cm

At least 4.9 cm

If the velocity of an object is zero at some point, then its acceleration must also be zero at that point.

False

If the velocity of an object is zero, then that object cannot be accelerating.

False

A 10-kg rock and 20-kg rock are dropped from the same height and experience no significant air resistance. If it takes the 20-kg rock a time T to reach the ground, what time will it take the 10-kg rock to reach the ground? 4T 2T T T/2 T/4

T

Suppose that a car traveling to the west begins to slow down as it approaches a traffic light. Which of the following statements about its acceleration is correct? The acceleration is toward the east. Since the car is slowing down, its acceleration must be negative. The acceleration is zero. The acceleration is toward the west.

The acceleration is toward the east.

Brick A is dropped from the top of a building. Brick B is thrown straight down from the same building, and neither one experiences appreciable air resistance. Which statement about their accelerations is correct? The acceleration of A is greater than the acceleration of B. The acceleration of B is greater than the acceleration of A. The two bricks have exactly the same acceleration. Neither brick has any acceleration once it is released.

The two bricks have exactly the same acceleration.

An auto manufacturer advertises that their car can go "from zero to sixty in eight seconds." This is a description of what characteristic of the car's motion? average speed instantaneous speed average acceleration instantaneous acceleration displacement

average acceleration