Q: A train engine pulls five identical freight cars, each weighing $$90.0\ \mathrm{kN}. $$The train reaches $$15.0\ \mathrm{m/s} in$$ $$5.00\ \mathrm{min}. $$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 for an object moving from point A to point B along a curved path?

Accepted Answer

Displacement is the straight-line vector from A to B, while distance is the total length of the path traveled.

Question 2

A car moves from position $$\vec{x}_0 = 2\ \mathrm{m} to$$ $$\vec{x} = 7\ \mathrm{m} in 5 $$seconds. What is the car's average velocity?

Accepted Answer

$$\displaystyle \frac{7\ \mathrm{m} - 2\ \mathrm{m}}{5\ \mathrm{s}} = 1\ \mathrm{m/s}$$

Question 3

A butterfly flies from point a to point e, $$6.0\ \mathrm{m} at$$ $$38^\circ$$ north of east, in $$12\ \mathrm{s}. $$What is the magnitude of its average velocity?

Accepted Answer

$$0.50\ \mathrm{m/s}$$

Question 4

Which of the following statements about velocity and speed is correct?

Accepted Answer

Velocity is a vector quantity, while speed is a scalar.

Question 5

A train travels 18 km at $$27^\circ$$ west of south, then 17 km due south, then 48 km at $$13^\circ$$ north of east. What is the magnitude of the total displacement?

Accepted Answer

$$45\ \mathrm{km}$$

Question 6

Given the velocity-time graph of an object moving with constant velocity, what does the area under the curve represent?

Accepted Answer

The object's displacement

Question 7

A 1.0 kg brick slides down a frictionless roof inclined at $$30.0^\circ to $$the horizontal. If it starts from rest, what is its speed after $$0.90\ \mathrm{s}$$?

Accepted Answer

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

Question 8

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 9

Which of the following best describes Newton’s Second Law of Motion?

Accepted Answer

$$\sum \vec{F} = m \vec{a}$$

Question 10

A train engine pulls five identical freight cars, each weighing $$90.0\ \mathrm{kN}. $$The train reaches $$15.0\ \mathrm{m/s} in$$ $$5.00\ \mathrm{min}. $$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 11

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 12

A car accelerates from rest to $$260\ \mathrm{km/h} in$$ $$29\ \mathrm{s}. $$What is its average acceleration in $$\mathrm{m/s}^2$$?

Accepted Answer

$$2.49\ \mathrm{m/s}^2$$

Question 13

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

Accepted Answer

The object moves with constant velocity.

Question 14

A dragster slows from $$28\ \mathrm{m/s} to$$ $$13\ \mathrm{m/s} in$$ $$3.0\ \mathrm{s}. $$What is its average acceleration?

Accepted Answer

$$-5.0\ \mathrm{m/s}^2$$

Question 15

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

Accepted Answer

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

Question 16

A cyclist rides $$400\ \mathrm{m}$$ east in $$200\ \mathrm{s}$$, stops for $$400\ \mathrm{s}$$, then rides $$400\ \mathrm{m}$$ west in $$400\ \mathrm{s}. $$What is the average velocity for the entire trip?

Accepted Answer

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

Question 17

A block of mass $$m$$ slides down a frictionless incline of angle $$	heta. $$What is the acceleration of the block?

Accepted Answer

$$g \sin 	heta$$

Question 18

Which of the following best describes the relationship between mass and acceleration for a given net force?

Accepted Answer

Acceleration is inversely proportional to mass.

Question 19

A suitcase is pulled with a force $$F at an $$angle $$	heta$$ above the horizontal. Which equation gives the normal force $$N on $$the suitcase?

Accepted Answer

$$N = mg - F \sin 	heta$$

Acceleration and Newton’s Second Law: Position, Displacement, Velocity, and Force

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