Q: A $$5\ \mathrm{kg}$$ object is dropped from rest. What is its velocity after $$3\ \mathrm{s}$$? (Assume $$g = 9.8\ \mathrm{m/s^2$})$$

$$v = g t = 9.8 \times 3 = 29.4\ \mathrm{m/s}$$

Question 1

Which of the following best describes the scientific method as applied in physics?

Accepted Answer

A process involving observation, hypothesis formation, experimentation, and analysis.

Question 2

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

Accepted Answer

$$a = \dfrac{20}{5} = 4\ \mathrm{m/s^2$}$$

Question 3

Which of the following is a vector quantity?

Accepted Answer

Displacement

Question 4

A ball is thrown straight up with an initial velocity of $$15\ \mathrm{m/s}. $$Neglecting air resistance, what is its velocity at the highest point?

Accepted Answer

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

Question 5

Which equation correctly relates displacement ($$x$$), initial velocity ($$v_0$$), acceleration ($$a$$), and time ($$t) $$for constant acceleration?

Accepted Answer

$$x = v_0$ t + \dfrac{1}{2} a t^2$

Question 6

A projectile is launched at an angle of $$30^\circ$$ with an initial speed of $$40\ \mathrm{m/s}. $$What is the initial vertical component of its velocity?

Accepted Answer

$$v_{y0} = 40 \sin 30^\circ = 20\ \mathrm{m/s}$$

Question 7

Which of the following statements about Newton's First Law is correct?

Accepted Answer

An object will remain at rest or in uniform motion unless acted upon by a net force.

Question 8

A $$2\ \mathrm{kg}$$ block is pulled by a force of $$10\ \mathrm{N} on a $$frictionless surface. What is its acceleration?

Accepted Answer

$$a = \dfrac{10}{2} = 5\ \mathrm{m/s^2$}$$

Question 9

Which of the following best describes the difference between mass and weight?

Accepted Answer

Mass is the amount of matter in an object; weight is the force due to gravity acting on that mass.

Question 10

A $$5\ \mathrm{kg}$$ object is dropped from rest. What is its velocity after $$3\ \mathrm{s}$$? (Assume $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$v = g t = 9.8 	imes 3 = 29.4\ \mathrm{m/s}$$

Question 11

Which of the following is NOT a fundamental SI unit?

Accepted Answer

Newton

Question 12

A car travels $$100\ \mathrm{km}$$ north, then $$50\ \mathrm{km}$$ east. What is the magnitude of its displacement?

Accepted Answer

$$\sqrt{100^2$ + 50^2$} = 111.8\ \mathrm{km}$$

Question 13

Which of the following best describes the concept of inertia?

Accepted Answer

The tendency of an object to resist changes in its motion.

Question 14

A $$3\ \mathrm{kg}$$ object moving at $$4\ \mathrm{m/s}$$ collides with a stationary $$2\ \mathrm{kg}$$ object. If they stick together, what is their final velocity?

Accepted Answer

$$v_f = \dfrac{3 	imes 4}{3 + 2} = 2.4\ \mathrm{m/s}$$

Question 15

Which of the following is the correct expression for Newton's Second Law?

Accepted Answer

$$F = m a$$

Question 16

A $$10\ \mathrm{kg}$$ box is at rest on a horizontal surface. The coefficient of static friction is $$0.4. $$What is the maximum force that can be applied before the box starts to move? (Assume $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$F_{max} = \mu_s m g = 0.4 	imes 10 	imes 9.8 = 39.2\ \mathrm{N}$$

Question 17

Which of the following is true about the acceleration of an object in free fall near Earth's surface?

Accepted Answer

It is constant and equal to $$9.8\ \mathrm{m/s^2$}$$ downward.

Question 18

A runner completes a $$400\ \mathrm{m}$$ lap in $$50\ \mathrm{s}. $$What is their average speed?

Accepted Answer

$$\dfrac{400}{50} = 8\ \mathrm{m/s}$$

Question 19

Which of the following best describes the difference between average velocity and instantaneous velocity?

Accepted Answer

Average velocity is measured over a time interval; instantaneous velocity is measured at a specific moment.

Physics Midterm Study Guide: Structured Notes on Introductory Physics Topics

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