Question 1

A dragster moves from $$x_1 = 19$$\ \mathrm{m}$$ at t_1$ = 1.0\ \mathrm{s} to$$ $$x_2 = 277$$\ \mathrm{m}$$ at t_2$ = 4.0\ \mathrm{s}. $$What is the average $$x-$$velocity of the dragster during this interval?

Accepted Answer

$$v_{\mathrm{av}-x} = \dfrac{277\ \mathrm{m} - 19\ \mathrm{m}}{4.0\ \mathrm{s} - 1.0\ \mathrm{s}} = 86\ \mathrm{m/s}$$

Question 2

A truck moves from $$x_1 = 277$$\ \mathrm{m}$$ at t_1$ = 16.0\ \mathrm{s} to$$ $$x_2 = 19$$\ \mathrm{m}$$ at t_2$ = 25.0\ \mathrm{s}. $$What is the average $$x-$$velocity of the truck?

Accepted Answer

$$v_{\mathrm{av}-x} = \dfrac{19\ \mathrm{m} - 277\ \mathrm{m}}{25.0\ \mathrm{s} - 16.0\ \mathrm{s}} = -28.7\ \mathrm{m/s}$$

Question 3

Which of the following best describes the instantaneous $$x-$$velocity at a given point on a position-time ($$x vs$$ $$t) $$graph?

Accepted Answer

The slope of the tangent to the $$x vs$$ $$t$$ curve at that point.

Question 4

A car is initially traveling at $$v_{0x} = 15\ \mathrm{m/s}$$ and accelerates at $$a_x = 2.0\ \mathrm{m/s}^2$$ for $$t = 5.0\ \mathrm{s}. $$What is its velocity after $$5.0\ \mathrm{s}$$?

Accepted Answer

$$v_x = v_{0x} + a_x t = 15\ \mathrm{m/s} + (2.0\ \mathrm{m/s}^2)(5.0\ \mathrm{s}) = 25\ \mathrm{m/s}$$

Question 5

A motorcyclist starts at $$x_0 = 5.0$$\ \mathrm{m}$$ with v$$_{0x} = 15\ \mathrm{m/s}$$ and accelerates at a_x = 4.0$$\ \mathrm{m/s}^2$$. What is his position at t = 2.0$$\ \mathrm{s}$$?

Accepted Answer

$$x = x_0$ + v_{0x} t + \dfrac{1}{2} a_x t^2$ = 5.0\ \mathrm{m} + (15\ \mathrm{m/s})(2.0\ \mathrm{s}) + 0.5 	imes 4.0\ \mathrm{m/s}^2 	imes (2.0\ \mathrm{s})^2$ = 43\ \mathrm{m}$$

Question 6

Which of the following statements is true about the sign of $$x-$$velocity and $$x-$$coordinate?

Accepted Answer

If the $$x-$$coordinate is positive and increasing, the $$x-$$velocity is positive.

Question 7

A bicyclist is moving to the left. If the positive $$x-$$direction is chosen to the right, what is the sign of the bicyclist's $$x-$$velocity?

Accepted Answer

Negative

Question 8

Which of the following is the correct formula for the average $$x-$$acceleration of a particle in straight-line motion?

Accepted Answer

$$a_{\mathrm{av}-x} = \dfrac{v_{2x} - v_{1x}}{t_2$ - t_1$}$$

Question 9

A particle moves with constant $$x-$$acceleration $$a_x. $$Which of the following is true about its $$x-$$velocity?

Accepted Answer

The $$x-$$velocity changes by equal amounts in equal time intervals.

Question 10

A car is moving in the $$+x-$$direction and slowing down. What is the sign of its acceleration?

Accepted Answer

Negative

Question 11

Which of the following best describes the motion of a particle if its $$x-$$velocity is positive and increasing?

Accepted Answer

The particle is moving in the $$+x-$$direction and speeding up.

Question 12

A position-time graph for a particle is a straight line with a positive slope. What does this indicate about the particle's motion?

Accepted Answer

The particle is moving with constant positive velocity.

Question 13

A particle's $$x-$$velocity is zero at a certain instant, but its $$x-$$acceleration is negative. What will happen to the particle immediately after this instant?

Accepted Answer

It will start moving in the $$-x-$$direction and speed up.

Question 14

Which of the following objects has a typical velocity magnitude closest to $$30\ \mathrm{m/s}$$?

Accepted Answer

A car on the freeway

Question 15

A particle moves from $$x_1 = -10$$\ \mathrm{m}$$ to x_2$ = 10\ \mathrm{m} in$$ $$4\ \mathrm{s}. $$What is its average $$x-$$velocity?

Accepted Answer

$$v_{\mathrm{av}-x} = \dfrac{10\ \mathrm{m} - (-10\ \mathrm{m})}{4\ \mathrm{s}} = 5\ \mathrm{m/s}$$

Question 16

If a particle's $$x-$$velocity is negative and decreasing (becoming more negative), what can you say about its acceleration?

Accepted Answer

The particle is moving in the $$-x-$$direction and speeding up; acceleration is negative.

Motion Along a Straight Line: Displacement, Velocity, and Acceleration

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