Question 1

A car starts from rest and accelerates at a constant rate of $$a = 15\ \mathrm{km/h^2$}$$ along a straight road. What is the velocity of the car after $$5.0\ \mathrm{s}$$? (Assume $$1\ \mathrm{km/h} = 0.278\ \mathrm{m/s})$$

Accepted Answer

$$v = 75\ \mathrm{km/h}$$

Question 2

A car is moving with an initial velocity of $$15.0\ \mathrm{m/s}$$ and slows down with a constant acceleration of $$-2.0\ \mathrm{m/s^2$}. $$What is its velocity after $$5.0\ \mathrm{s}$$?

Accepted Answer

$$v = 5.0\ \mathrm{m/s}$$

Question 3

Which of the following best describes the relationship between the sign of velocity and the sign of acceleration for an object that is slowing down?

Accepted Answer

Velocity and acceleration have opposite signs.

Question 4

Given the position vs. time graph of an object is a downward-opening parabola, what can you say about the object's acceleration?

Accepted Answer

The acceleration is negative and constant.

Question 5

If the velocity of a car changes from $$-15.0\ \mathrm{m/s} to$$ $$-5.0\ \mathrm{m/s} in$$ $$4.0\ \mathrm{s}$$, what is the average acceleration?

Accepted Answer

$$a_{av} = +2.5\ \mathrm{m/s^2$}$$

Question 6

Which of the following statements is TRUE about the area under a velocity vs. time graph?

Accepted Answer

It represents the displacement of the object.

Question 7

A car moves in the negative $$x-$$direction and slows down. What is the sign of its acceleration?

Accepted Answer

Positive

Question 8

If an object’s velocity-time graph is a straight line with a positive slope, what does this indicate about the object’s motion?

Accepted Answer

The object is accelerating at a constant positive rate.

Question 9

A car starts at $$x_1 = 0$ with v$$_{1x} = 0$$ and accelerates at a = 15$$\ \mathrm{km/h/s}$$. What is the car’s velocity at t = 2.0$$\ \mathrm{s}$$?

Accepted Answer

$$v = 30\ \mathrm{km/h}$$

Question 10

Which of the following is the correct calculus definition of instantaneous acceleration?

Accepted Answer

$$a(t) = \frac{dv}{dt} = \frac{d^2$x}{dt^2$}$$

Question 11

A car is moving forward and speeding up. Which of the following is true about the signs of its velocity and acceleration?

Accepted Answer

Both velocity and acceleration are positive.

Question 12

If the slope of a position vs. time graph is zero at a certain instant, what does this indicate about the object’s motion at that instant?

Accepted Answer

The object is at rest.

Question 13

Which of the following best describes 'deceleration' in physics?

Accepted Answer

An acceleration that decreases the speed of an object, regardless of sign.

Question 14

A car’s velocity changes from $$20\ \mathrm{m/s} to$$ $$0\ \mathrm{m/s} in$$ $$4\ \mathrm{s}. $$What is the average acceleration?

Accepted Answer

$$a_{av} = -5\ \mathrm{m/s^2$}$$

Question 15

Which of the following is NOT a correct interpretation of the area under an acceleration vs. time graph?

Accepted Answer

It gives the initial velocity of the object.

Question 16

A car is moving in the negative $$x-$$direction and speeds up. What is the sign of its acceleration?

Accepted Answer

Negative

Question 17

If the velocity of an object is zero at a certain instant, what can you conclude about its acceleration at that instant?

Accepted Answer

Nothing definite; acceleration could be positive, negative, or zero.

Question 18

Which of the following is the correct formula for average velocity over a time interval $$\Delta t$$?

Accepted Answer

$$v_{av} = \frac{\Delta x}{\Delta t}$$

Acceleration and Kinematic Graphs in One-Dimensional Motion

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