Q: Which equation correctly represents Newton’s Second Law?

$$\vec{F}_{\text{net}} = m\vec{a}$$

Question 1

A person pushes a box across a rough floor. If the box moves at constant velocity, which statement best describes the forces acting on it?

Accepted Answer

The applied force is equal to the kinetic frictional force.

Question 2

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

Accepted Answer

An object at rest remains at rest, and an object in motion continues in motion at constant speed in a straight line unless acted on by a nonzero net force.

Question 3

A 10 kg object is on Earth, where $$g = 9.8\ 	ext{m/s}^2. $$What is the weight of the object?

Accepted Answer

$$98\ 	ext{N}$$

Question 4

A rocket launches upward. According to Newton’s Third Law, what is the reaction force to the rocket’s engines pushing exhaust gases downward?

Accepted Answer

The exhaust gases push the rocket upward.

Question 5

A box sits on a table. Which force is responsible for the table supporting the box?

Accepted Answer

The normal force exerted by the table.

Question 6

If two objects are connected by a massless rope and pulled with a force $$F$$, what is the acceleration of the system if their masses are $$m_1$$ and $$m_2$$?

Accepted Answer

$$a = \frac{F}{m_1$ + m_2$}$$

Question 7

A car suddenly stops and the passenger lurches forward. Which law explains this phenomenon?

Accepted Answer

Newton’s First Law

Question 8

Which equation correctly represents Newton’s Second Law?

Accepted Answer

$$\vec{F}_{	ext{net}} = m\vec{a}$$

Question 9

A 5 kg box is pulled with a force of 20 N on a frictionless surface. What is its acceleration?

Accepted Answer

$$4\ 	ext{m/s}^2$$

Question 10

A box is at rest on a horizontal surface. Which statement is true about the forces acting on it?

Accepted Answer

The net force is zero.

Question 11

A person tries to push a heavy box but it does not move. Which force is balancing the applied force?

Accepted Answer

Static friction

Question 12

Which of the following is NOT a fundamental force in nature?

Accepted Answer

Friction

Question 13

If the coefficient of kinetic friction between a box and the floor is $$\mu_k = 0.2$$ and the normal force is $$50\ 	ext{N}$$, what is the force of kinetic friction?

Accepted Answer

$$10\ 	ext{N}$$

Question 14

A book is held against a wall by a hand. Which force prevents the book from sliding down?

Accepted Answer

Frictional force between the book and wall

Question 15

Which statement about action-reaction pairs is correct?

Accepted Answer

They act on different objects and are equal in magnitude and opposite in direction.

Question 16

A box is being pulled across a surface and accelerates. Which force is responsible for the acceleration?

Accepted Answer

The net force acting on the box.

Question 17

If the static friction coefficient is $$\mu_s = 0.4$$ and the normal force is $$100\ 	ext{N}$$, what is the maximum static friction force?

Accepted Answer

$$40\ 	ext{N}$$

Question 18

Which property of matter is measured by mass?

Accepted Answer

Inertia

Question 19

A box is pulled with a force of $$F$$ but does not move. Which equation describes the relationship between the applied force and static friction?

Accepted Answer

$$F \leq \mu_s N$$

Question 20

Which of the following statements about friction is correct?

Accepted Answer

Static friction can take any value up to a maximum.

Newton's Laws of Motion and Forces: Structured Study Notes

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