Q: A train engine pulls five identical freight cars (each $$90.0\ \mathrm{kN}) to$$ $$15.0\ \mathrm{m/s} in$$ $$5.00\ \mathrm{min}. $$What is the magnitude of the force the coupling exerts on the last car (ignore friction)?

$$4.50 \times 10^3$\ \mathrm{N}$$

Question 1

Which of the following best describes the difference between displacement and distance traveled?

Accepted Answer

Displacement is the straight-line change in position (vector), while distance is the total length of the path traveled (scalar).

Question 2

A car moves from position $$\vec{x}_0 = 2.0\ \mathrm{m} to$$ $$\vec{x} = 7.0\ \mathrm{m}. $$What is the displacement $$\Delta \vec{x}$$?

Accepted Answer

$$\Delta \vec{x} = 5.0\ \mathrm{m}$$

Question 3

Given the following trip: 18 km at $$27^\circ$$ west of south, 17 km due south, and 48 km at $$13^\circ$$ north of east, what is the magnitude of the total displacement?

Accepted Answer

$$45\ \mathrm{km}$$

Question 4

Which equation correctly gives the average velocity $$\vec{v}_{\mathrm{av}}$$ over a time interval $$\Delta t$$?

Accepted Answer

$$\vec{v}_{\mathrm{av}} = \frac{\Delta \vec{x}}{\Delta t}$$

Question 5

A runner completes a 400 m lap in 50 s, ending at the starting point. What is the average velocity?

Accepted Answer

$$0\ \mathrm{m/s}$$

Question 6

The slope of a position vs. time graph at a given instant represents:

Accepted Answer

The object's instantaneous velocity

Question 7

A car accelerates from rest to $$20\ \mathrm{m/s} in$$ $$5\ \mathrm{s}. $$What is its average acceleration?

Accepted Answer

$$4\ \mathrm{m/s}^2$$

Question 8

Which of the following statements about acceleration is correct?

Accepted Answer

Acceleration is the rate of change of velocity and can be in the opposite direction to velocity.

Question 9

A suitcase of mass $$36.0\ \mathrm{kg} is $$pulled with a force of $$65.0\ \mathrm{N} at$$ $$40.0^\circ$$ above the horizontal. If the coefficient of kinetic friction is $$\mu_k = 0.13$$, what is the acceleration of the suitcase?

Accepted Answer

$$0.260\ \mathrm{m/s}^2$$

Question 10

A brick slides down a frictionless roof inclined at $$30.0^\circ$$ with respect to the horizontal. If it starts from rest, what is its speed after $$0.90\ \mathrm{s}$$?

Accepted Answer

$$4.4\ \mathrm{m/s}$$

Question 11

A train engine pulls five identical freight cars (each $$90.0\ \mathrm{kN}) to$$ $$15.0\ \mathrm{m/s} in$$ $$5.00\ \mathrm{min}. $$What is the magnitude of the force the coupling exerts on the last car (ignore friction)?

Accepted Answer

$$4.50 	imes 10^3$\ \mathrm{N}$$

Question 12

Two blocks, $$m_1 = 26.0$$\ \mathrm{kg}$$ and m_2$ = 42.0\ \mathrm{kg}$$, are connected by a cord over a frictionless pulley. What is the acceleration of the system?

Accepted Answer

$$2.31\ \mathrm{m/s}^2$$

Question 13

Which of the following is the correct SI unit for force?

Accepted Answer

$$\mathrm{kg\cdot m/s^2$}$$

Question 14

If the net force on an object is zero, which of the following must be true?

Accepted Answer

The object moves with constant velocity or is at rest.

Question 15

A cyclist moves with a constant velocity of $$10\ \mathrm{m/s}$$ for $$30\ \mathrm{s}. $$What is the displacement?

Accepted Answer

$$300\ \mathrm{m}$$

Question 16

Which of the following best describes mass in the context of Newton's second law?

Accepted Answer

Mass is a measure of an object's inertia, or resistance to changes in velocity.

Question 17

A car's velocity changes from $$15\ \mathrm{m/s}$$ east to $$10\ \mathrm{m/s}$$ west in $$5\ \mathrm{s}. $$What is the average acceleration (east is positive)?

Accepted Answer

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

Question 18

Which of the following is NOT a step in the problem-solving strategy for Newton’s laws?

Accepted Answer

Ignore the directions of forces when adding them.

Question 19

A block slides down a frictionless incline of angle $$	heta. $$Which component of gravity causes the block to accelerate down the incline?

Accepted Answer

$$mg \sin 	heta$$

Acceleration and Newton’s Second Law: Motion, Vectors, and Forces

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