Q: When an object stops, which is true?

Velocity = 0, Acceleration $$\neq 0$$

Question 1

Which of the following best describes the difference between distance and displacement for a runner who jogs 8 m east and then 3 m west along a straight path?

Accepted Answer

Distance = 11 m, Displacement = 5 m east

Question 2

A car is cruising at $$15\ \mathrm{m/s}$$ and then accelerates at $$2.0\ \mathrm{m/s^2$}$$ for $$5.0\ \mathrm{s}. $$What distance does the car travel during this period of acceleration?

Accepted Answer

$$75\ \mathrm{m}$$

Question 3

Which statement about acceleration is correct?

Accepted Answer

If velocity is negative and acceleration is negative, the object speeds up.

Question 4

A cheetah is sprinting at $$20.0\ \mathrm{m/s}$$ and slows down uniformly to rest in $$5.00\ \mathrm{s}. $$How far does the cheetah travel while decelerating?

Accepted Answer

$$25.0\ \mathrm{m}$$

Question 5

Given the equation $$x = vt - 2a/t^2$, where x$ is displacement, v$ is velocity, a$ is acceleration, and t$ is time, is this equation dimensionally correct?

Accepted Answer

No, the second term $$2a/t^2$$ does not have dimensions of length.

Question 6

A vector has components $$A_x = -8$$ units and $$A_y = 6$$ units. What angle does this vector make with the positive x-axis?

Accepted Answer

$$36.9^\circ$$ above the negative x-axis

Question 7

If all components of a vector are negative, what can be said about the magnitude of the vector?

Accepted Answer

The magnitude is positive.

Question 8

A force $$F$$ has a magnitude of $$25.0\ \mathrm{N}$$ and points at an angle of $$30^\circ$$ north of east. What is the north (y) component of this force?

Accepted Answer

$$25.0 	imes \sin(30^\circ)$$

Question 9

A rock starts running from rest and accelerates uniformly along a straight path. It covers $$2.0\ \mathrm{m} in $$the first second. What will its displacement be after $$5$$ seconds?

Accepted Answer

$$10.0\ \mathrm{m}$$

Question 10

A car moves along a straight road. Its velocity at $$t = 0 is$$ $$20\ \mathrm{m/s}$$ east. It decelerates uniformly and comes to a stop after $$8\ \mathrm{s}. It $$then accelerates in the opposite direction (west) and reaches $$16\ \mathrm{m/s}$$ after $$4\ \mathrm{s}. $$What is the average acceleration for the entire motion? Take east as positive.

Accepted Answer

$$-0.4\ \mathrm{m/s^2$}$$

Question 11

Which of the following is true about the instantaneous velocity of an object for a round trip between two points?

Accepted Answer

It can be greater than, less than, or equal to zero at different times.

Question 12

A ball is moving to the left with a velocity of $$-6\ \mathrm{m/s}$$ when it is observed to be gradually coming to rest. What can you conclude about the direction of its acceleration?

Accepted Answer

Acceleration is positive.

Question 13

How many significant figures are in the number $$0.040$$?

Accepted Answer

2

Question 14

Which of the following is the correct result for $$\dfrac{72.0 - 15.60}{0.982 + 4.3}$$ with the correct number of significant figures?

Accepted Answer

$$10.9$$

Question 15

Which velocity-time graph best matches an object that moves rightward, slows to a stop, then moves leftward?

Accepted Answer

A graph that starts positive, decreases to zero, then becomes negative.

Question 16

When an object stops, which is true?

Accepted Answer

Velocity = 0, Acceleration $$
eq 0$$

Question 17

Which of the following is NOT a correct statement about acceleration?

Accepted Answer

Acceleration always means slowing down.

Question 18

Which of the following is a correct dimensional analysis for acceleration?

Accepted Answer

$$[a] = L/T^2$

PHYS1403: Selected Practice Problems and Concepts in 1D Kinematics and Measurement

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