Q: Which of the following is a correct mathematical expression for the scalar (dot) product of two vectors $$\vec{A}$$ and $$\vec{B}$$?

$$\vec{A} \cdot \vec{B} = AB \cos \theta$$

Question 1

Which of the following best describes Newton's third law of motion?

Accepted Answer

For every action, there is an equal and opposite reaction.

Question 2

A 2 kg object is acted upon by a net force of $$10\ \mathrm{N} to $$the right. What is its acceleration?

Accepted Answer

$$5\ \mathrm{m/s^2$} to $$the right

Question 3

Which of the following statements correctly distinguishes between mass and weight?

Accepted Answer

Mass is a measure of the amount of matter in an object, while weight is the gravitational force acting on that mass.

Question 4

A box rests on a horizontal surface. Which force is always perpendicular to the surface and acts upward on the box?

Accepted Answer

Normal force

Question 5

According to Newton's law of universal gravitation, what is the magnitude of the gravitational force between two masses $$m_1$$ and $$m_2$$ separated by a distance $$r$$?

Accepted Answer

$$F = G \dfrac{m_1$ m_2$}{r^2$}$$

Question 6

A car moves in a circle of radius $$20\ \mathrm{m} at a $$constant speed of $$10\ \mathrm{m/s}. $$What is the magnitude of its acceleration?

Accepted Answer

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

Question 7

Which of the following best describes a resistive force?

Accepted Answer

A force that always acts opposite to the direction of motion and opposes movement.

Question 8

For a falling object experiencing air resistance proportional to its speed, what is the expression for terminal speed $$v_t$$?

Accepted Answer

$$v_t = \dfrac{mg}{b}$$

Question 9

Which of the following is a correct mathematical expression for the scalar (dot) product of two vectors $$\vec{A}$$ and $$\vec{B}$$?

Accepted Answer

$$\vec{A} \cdot \vec{B} = AB \cos 	heta$$

Question 10

A force of $$5\ \mathrm{N}$$ acts on an object and moves it $$3\ \mathrm{m} in $$the direction of the force. How much work is done?

Accepted Answer

$$15\ \mathrm{J}$$

Question 11

Which of the following is the correct formula for the work done by a spring force when stretched or compressed by a distance $$x$$ from equilibrium?

Accepted Answer

$$W = -\dfrac{1}{2} k x^2$

Question 12

Which of the following is the correct mathematical definition of kinetic energy for an object of mass $$m$$ moving at speed $$v$$?

Accepted Answer

$$K = \dfrac{1}{2} m v^2$

Question 13

Which of the following is an example of a conservative force?

Accepted Answer

Gravitational force

Question 14

A ball is dropped from a height $$h$$ with no air resistance. Which equation correctly expresses conservation of mechanical energy for the ball-Earth system?

Accepted Answer

$$mgh = \dfrac{1}{2} m v^2$

Question 15

Which of the following statements about power is correct?

Accepted Answer

Power is the rate at which work is done.

Question 16

A person lifts a $$50\ \mathrm{kg}$$ box vertically upward $$2\ \mathrm{m} in$$ $$4\ \mathrm{s}. $$What is the average power output? (Assume $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$245\ \mathrm{W}$$

Question 17

Which of the following is the correct formula for the average power $$P_{avg}$$ delivered by a constant force $$F$$ moving an object at constant velocity $$v$$?

Accepted Answer

$$P_{avg} = F v$$

Question 18

A block slides down a rough incline, losing $$100\ \mathrm{J} of $$mechanical energy to friction. If it started with $$300\ \mathrm{J} of $$potential energy, what is its kinetic energy at the bottom?

Accepted Answer

$$200\ \mathrm{J}$$

Question 19

Which of the following statements about the system boundary in energy analysis is correct?

Accepted Answer

Changing the system boundary changes which forces are considered external, but not the underlying physics.

Guided Study: Newton's Laws, Forces, Gravitation, Work, Energy, and Power

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