Physics - Unit 1 Review

A cheetah running at a velocity of 18 m/s accelerates 1.4 m/s². How long does it take for the cheetah to reach his maximum speed of 33 m/s?

• 10.7 seconds

• 12.5 seconds

• 15.0 seconds

• 20.0 seconds

A marathon runner runs with an average velocity of 5.5 m/s. How long in seconds does it take for the runner to travel 158 m?

• 28.7 seconds

• 30 seconds

• 25.5 seconds

• 32 seconds

How long (in seconds) will it take a dragster to complete a quarter-mile (402 meters) race if it is accelerating 26.0 m/s² the entire time?

• 5.6 seconds

• 6.0 seconds

• 6.5 seconds

• 7.0 seconds

A fighter jet accelerates at an average rate of 10.43 m/s² and takes off 250 m down the runway. How long does it take the jet to take-off?

• 6.9 seconds

• 7.8 seconds

• 8.5 seconds

• 9.2 seconds

At what initial velocity do you have to throw a rock straight up to reach a maximum height of 30 meters?

• 10 m/s

• 15 m/s

• 20 m/s

• 24 m/s

If you throw the rock with an initial velocity of 18 m/s, how high will the rock travel before falling back to the ground?

• 16.5 meters

• 18 meters

• 20.5 meters

• 22 meters

You throw the rock again, which reaches its maximum height in 3.0 seconds. What is the rock’s maximum height?

• 44 meters

• 30 meters

• 15 meters

• 60 meters

The graph in the figure shows the position of a particle as it travels along the x-axis. What is the magnitude of the instantaneous velocity of the particle when t = 1.0 s?

• 0 m/s

• 1 m/s

• 2 m/s

• 3 m/s

Answer explanation

The instantaneous velocity is the slope of the line at the time in question.

At 1 second, the slope appears to be the slope of the line from t=0s to t=1s.

The rise in that case is about 3 meters for the run of 1 second. The slope is the rise over the run, or 3 meters/1 second, or 3 m/s.

Which of the following graphs represent an object having zero acceleration?

• only graph a

• only graph b

• graphs a and b

• graphs b and c

• graphs c and d

Answer explanation

Graph (a): For position time graphs (x vs. t) the slope is the velocity, therefore, a constant velocity will be indicated by a constant slope.

Graph (b), (c), (d): For a velocity-time graph (v vs. t), a constant velocity will be indicated by a line with the same value throughout (a horizontal line). Graph (a) is a horizontal line, therefore indicates constant velocity.

The graph in the figure shows the position of an object as a function of time. The letters H-L represent particular moments of time. At which moment in time is the speed of the object the greatest?

• H

• I

• J

• K

• L

Answer explanation

Direction does not matter for the speed of an object. The highest speed will be indicated by the steepest slope, regardless of whether it is positive or negative.