Question 1

A cyclist rides 3 km west and then turns around and rides 2 km east. What is her total displacement?

Accepted Answer

$$\Delta x = -1\ \mathrm{km}$$

Question 2

Which of the following statements about distance and displacement is correct?

Accepted Answer

Distance is always positive, while displacement can be positive, negative, or zero.

Question 3

A race car is at $$19\ \mathrm{m}$$ from the origin at $$t=1.0\ \mathrm{s}$$, and at $$277\ \mathrm{m}$$ from the origin at $$t=4.0\ \mathrm{s}. $$What is the car's displacement?

Accepted Answer

$$\Delta x = 258\ \mathrm{m}$$

Question 4

Which of the following best describes average velocity?

Accepted Answer

Average velocity is the change in position divided by the time interval, and is a vector.

Question 5

A swimmer swims 50.0 m in 24.0 s, then takes 48.0 s to swim back to the starting point. What is her average speed for the entire swim?

Accepted Answer

$$v_{\mathrm{avg}} = \frac{100.0\ \mathrm{m}}{72.0\ \mathrm{s}} = 1.39\ \mathrm{m/s}$$

Question 6

Under which condition is the magnitude of the average velocity of a particle moving in one dimension smaller than the average speed over the time interval?

Accepted Answer

When the particle reverses direction during its motion.

Question 7

A car moves to the left along a straight highway (positive x-axis to the left). Its initial velocity is $$15.0\ \mathrm{m/s}$$ and it slows down to $$5.0\ \mathrm{m/s} in$$ $$5.0\ \mathrm{s}. $$What is the car's average acceleration?

Accepted Answer

$$a_{\mathrm{avg}} = +2.0\ \mathrm{m/s}^2$$

Question 8

If velocity and acceleration are in opposite directions, what happens to the object's speed?

Accepted Answer

The object slows down.

Question 9

An object is moving along a straight line and has negative acceleration. What does this mean?

Accepted Answer

The object is slowing down.

Question 10

The slope of a position vs. time ($$x vs$$ $$t) $$graph represents:

Accepted Answer

Velocity

Question 11

A ball is thrown upward into the air. Neglecting air resistance, what happens to its acceleration after it leaves your hand?

Accepted Answer

It remains the same.

Question 12

Which equation gives the position $$x of an $$object in linear motion with constant velocity?

Accepted Answer

$$x = x_0$ + v_x t$$

Question 13

A jet accelerates from rest at a constant rate down a runway. If it travels $$1.20\ \mathrm{km} to $$reach a speed of $$220\ \mathrm{km/h}$$, what equation would you use to find the acceleration?

Accepted Answer

$$v^2$$ = $$v_0^2 + 2 a x$

Question 14

A racing cyclist slows down at a steady rate from $$15.0\ \mathrm{m/s} to$$ $$10.0\ \mathrm{m/s} in$$ $$4.00\ \mathrm{s}. $$How far does the cyclist travel while slowing down?

Accepted Answer

Question 15

For an object in free fall near Earth's surface, what is the acceleration due to gravity?

Accepted Answer

$$g = 9.80\ \mathrm{m/s}^2$$ downward

Question 16

A ball is thrown straight up with an initial velocity of $$20\ \mathrm{m/s}. $$How long does it take to reach its highest point? (Ignore air resistance.)

Accepted Answer

$$t = 2.04\ \mathrm{s}$$

Question 17

Which of the following is true about instantaneous velocity?

Accepted Answer

It is the velocity at a specific instant in time.

Question 18

The slope of a velocity vs. time ($$v vs$$ $$t) $$graph represents:

Accepted Answer

Acceleration

Question 19

A springbok jumps straight up and reaches a height of $$1.25\ \mathrm{m}. $$What is its speed just as it leaves the ground? (Ignore air resistance.)

Accepted Answer

$$v_0$$ = \sqrt{2 g h} = 4.95\ \mathrm{m/s}$$

Chapter 2: Linear Motion – One Dimensional Kinematics

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