Q: Two forces of $$5\ \mathrm{N}$$ each act perpendicular to each other on an object. What is the magnitude of the resultant force?

$$\sqrt{2} \times 5\ \mathrm{N} \approx 7.1\ \mathrm{N}$$

Question 1

According to Aristotle, which of the following best describes 'natural motion' for terrestrial objects?

Accepted Answer

Objects strive toward their proper place based on their composition of four elements.

Question 2

Galileo's experiment at the Leaning Tower of Pisa demonstrated that:

Accepted Answer

Objects of different weights fall together and hit the ground at the same time, except for air resistance.

Question 3

Which of the following statements best describes Newton's First Law of Motion?

Accepted Answer

Every object continues in its state of rest or uniform speed in a straight line unless acted on by a net external force.

Question 4

A hockey puck slides across ice and eventually stops. According to Galileo and Newton, why does it stop?

Accepted Answer

Because an external force, such as friction, acts against its motion.

Question 5

A painter’s scaffold is supported by two ropes. If the total downward weight is $$1300\ \mathrm{N}$$, and the upward tension in the ropes is $$900\ \mathrm{N}$$ and $$400\ \mathrm{N}$$, what is the net force acting on the scaffold?

Accepted Answer

$$900\ \mathrm{N} + 400\ \mathrm{N} - 1300\ \mathrm{N} = 0\ \mathrm{N}$$

Question 6

Which of the following is a vector quantity?

Accepted Answer

Force

Question 7

Two forces of $$5\ \mathrm{N}$$ each act perpendicular to each other on an object. What is the magnitude of the resultant force?

Accepted Answer

$$\sqrt{2} 	imes 5\ \mathrm{N} \approx 7.1\ \mathrm{N}$$

Question 8

A $$2\ \mathrm{lb}$$ bag of flour (approximately $$9\ \mathrm{N}) $$hangs from a scale. What forces act on the bag, and what is their sum?

Accepted Answer

An upward tension force and a downward gravitational force, which sum to zero.

Question 9

A crate is pushed across a floor at constant speed. Which statement best describes its equilibrium?

Accepted Answer

It is in dynamic equilibrium because the forward force equals the force of friction.

Question 10

If you stand on two bathroom scales and shift more weight to your left foot, which statement is true?

Accepted Answer

The sum of the readings on both scales equals your total weight.

Question 11

Which equation represents the equilibrium rule for forces acting on an object?

Accepted Answer

$$\sum \vec{F} = 0$$

Question 12

A ball rolls down an incline and up an opposing incline. If the second incline is less steep, what happens to the distance the ball travels?

Accepted Answer

The ball rolls farther to reach the same height.

Question 13

Which scenario best illustrates dynamic equilibrium?

Accepted Answer

A bowling ball rolling at constant speed before hitting pins.

Question 14

If an airplane flies horizontally at constant speed, what can be said about the forces acting on it?

Accepted Answer

The net force is zero; thrust equals air resistance.

Question 15

A person jumps straight up next to a wall. Why does the wall not crash into them as Earth moves?

Accepted Answer

Because the person retains their shared horizontal speed due to inertia.

Question 16

Which of the following is NOT a scalar quantity?

Accepted Answer

Acceleration

Question 17

If two forces act in opposite directions on an object, each with a magnitude of $$5\ \mathrm{N}$$, what is the net force?

Accepted Answer

$$0\ \mathrm{N}$$

Question 18

Which historical event directly challenged the Aristotelian view of a stationary Earth?

Accepted Answer

Copernicus's publication of the heliocentric model.

Question 19

What is the scientific unit of force, and how is it defined?

Accepted Answer

The newton (N), defined as $$1\ \mathrm{N} = 1\ \mathrm{kg} \cdot 1\ \mathrm{m}/\mathrm{s}^2$$

Newton’s First Law of Motion: Inertia and the Foundations of Classical Mechanics (Chapter 2)

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