Q: A projectile is launched at $$30^$$ above the horizontal with a speed of $$40\ \mathrm{m/s}. $$What is the initial vertical component of its velocity?

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

Q: A $$5\ \mathrm{kg}$$ box is pulled across a horizontal floor with a force of $$20\ \mathrm{N} at an $$angle of $$30^$$ above the horizontal. What is the horizontal component of the force?

$$20 \cos 30^ = 17.3\ \mathrm{N}$$

Question 1

A car travels east for 100 m, then north for 100 m. What is the magnitude of its displacement from the starting point?

Accepted Answer

$$141\ \mathrm{m}$$

Question 2

Which of the following best describes the difference between velocity and speed?

Accepted Answer

Speed is a scalar, velocity is a vector.

Question 3

A ball is thrown vertically upward with an initial velocity of $$v_0 = 20$$\ \mathrm{m/s}$$. Neglecting air resistance, what is its velocity after 2$$\ \mathrm{s}$$? (Take g = 9.8$$\ \mathrm{$$m/s^2$$}$$ downward)

Accepted Answer

$$0.4\ \mathrm{m/s}$$\ upward

Question 4

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

Accepted Answer

$$40 \sin 30^  = 20\ \mathrm{m/s}$$

Question 5

Which of Newton's Laws explains why passengers lurch forward when a car suddenly stops?

Accepted Answer

Newton's First Law

Question 6

A $$2\ \mathrm{kg}$$ block slides down a frictionless incline of height $$5\ \mathrm{m}. $$What is its speed at the bottom? ($$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$9.9\ \mathrm{m/s}$$

Question 7

A force of $$10\ \mathrm{N} is $$applied to a $$5\ \mathrm{kg}$$ object. What is its acceleration?

Accepted Answer

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

Question 8

A $$0.5\ \mathrm{kg}$$ ball is dropped from rest from a height of $$8\ \mathrm{m}. $$What is its velocity just before hitting the ground? ($$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$12.5\ \mathrm{m/s}$$\ downward

Question 9

Which equation would you use to find the displacement of an object under constant acceleration, given initial velocity $$v_i$$, acceleration $$a$$, and time $$t$$?

Accepted Answer

$$x = v_i t + \frac{1}{2} a t^2$

Question 10

A $$3\ \mathrm{kg}$$ object moving at $$4\ \mathrm{m/s}$$ collides and sticks to a $$2\ \mathrm{kg}$$ object at rest. What is their final velocity after collision?

Accepted Answer

$$2.4\ \mathrm{m/s}$$

Question 11

A $$60\ \mathrm{kg}$$ astronaut pushes against a $$120\ \mathrm{kg}$$ satellite in space. If the astronaut moves away at $$3\ \mathrm{m/s}$$, what is the satellite's velocity?

Accepted Answer

$$-1.5\ \mathrm{m/s}$$

Question 12

A $$5\ \mathrm{kg}$$ box is pulled across a horizontal floor with a force of $$20\ \mathrm{N} at an $$angle of $$30^ $$ above the horizontal. What is the horizontal component of the force?

Accepted Answer

$$20 \cos 30^  = 17.3\ \mathrm{N}$$

Question 13

Which of the following is true about the work done by gravity on a falling object?

Accepted Answer

It is positive and equals the loss in potential energy.

Question 14

A $$1\ \mathrm{kg}$$ object is moving at $$10\ \mathrm{m/s}. $$What is its kinetic energy?

Accepted Answer

$$50\ \mathrm{J}$$

Question 15

A $$2\ \mathrm{kg}$$ object is lifted $$3\ \mathrm{m}$$ vertically. How much work is done against gravity? ($$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$58.8\ \mathrm{J}$$

Question 16

A cyclist increases her speed from $$5\ \mathrm{m/s} to$$ $$15\ \mathrm{m/s}. By $$what factor does her kinetic energy increase?

Accepted Answer

Question 17

A $$10\ \mathrm{kg}$$ box is at rest on a frictionless surface. A $$50\ \mathrm{N}$$ force acts on it for $$4\ \mathrm{s}. $$What is its final velocity?

Accepted Answer

$$20\ \mathrm{m/s}$$

Question 18

A $$0.2\ \mathrm{kg}$$ ball is thrown horizontally at $$10\ \mathrm{m/s}$$ from a $$5\ \mathrm{m}$$ high table. How long does it take to hit the ground? ($$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$1.01\ \mathrm{s}$$

Question 19

Which of the following best describes the principle of conservation of energy?

Accepted Answer

Total energy in a closed system remains constant.

PCS120 Physics Exam Study Guide: Motion, Kinematics, Dynamics, Energy, and Work

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