Physics: Forces and the Laws of Motion

Question 1

What is the SI unit of force?

Answer 1

Newton

Question 2

What is the English unit of force?

Answer 2

Pound

Question 3

How many pounds per Newton are there?

Answer 3

0.225lb=1N

Question 4

How many Newtons per pound are there?

Answer 4

4.448N=1lb

Question 5

How do you derive Newtons from smaller SI units?

Answer 5

Newton = Kilogram x Meters per Second^2

Question 6

Is force a vector or a scalar quantity?

Answer 6

Vector

Question 7

What is Newton’s First Law?

Answer 7

An object at rest remains at rest, and an object in motion remains in motion, unless acted on by an outside force.

Question 8

What is described by Newton’s First Law?

Answer 8

Inertia

Question 9

What is the net force of an object?

Answer 9

The vector sum of all forces acting on an object

Question 10

What is the net force of a car travelling at a constant velocity?

Answer 10

0N

Question 11

What is Newton’s Second Law?

Answer 11

F=MA; Force=Mass x Acceleration

Question 12

Why do you need to know Newton’s Second Law?

Answer 12

For Ma. Because if you don’t learn Newton’s Second Law, you will fail physics, and if you fail physics, you won’t be able to graduate, and if you can’t graduate, you will have to work at McDonalds. If you have to work at McDonalds, you will have to live in a dirty trailer park, and if you have to live in a dirty trailer park, you will start doing drugs, and if you start doing drugs you will die and leave you ma all alone with no one to take care of her when she gets old.

Question 13

What is Newton’s Third Law?

Answer 13

Every action has an equal and opposite reaction

Question 14

What are the four field forces in order from strongest to weakest?

Answer 14

Strong nuclear Force, Electromagnetic force, weak nuclear force, Gravity

Question 15

What is the name of the force that stops us from going through the earth? (hint: it is the reaction to contact with the ground)

Answer 15

The force normal

Question 16

What is the friction that stops an object from moving?

Answer 16

Static friction

Question 17

What is the frictional force that retards the movement of an object in motion?

Answer 17

Kinetic friction

Question 18

A bag of sugar has a mass of 2.26 kg. What is its weight in newtons on the moon where the acceleration due to gravity is one-sixth that of Earth?

Answer 18

3.70 N

Question 19

The force of air resistance acting on a certain falling object is roughly proportional to the square of the object’s velocity. If the object falls fast enough, will the force of the air resistance eventually exceed the weight of the object and cause the object to move upwards? Explain.

Answer 19

No, because the object will just have reached equilibrium where the net force is 0, and will be falling at a constant velocity known as terminal velocity.

Question 20

What is the equation to find the gravitational potential energy?

Answer 20

GPE = mass x gravity x height

Question 21

What is the equation for elastic potential energy?

Answer 21

1/2 x spring constant x distance compressed or stretched^2

Question 22

How do you find the spring constant?

Answer 22

distance compressed/force needed to compress the spring to that distance