P2.2 - Newton’s laws

Question 1

When do forces arise

Answer 1

Pairs of forces arise when objects interact

Question 2

What happens in an interaction pair?

Answer 2

each force acts on a different object

The forces are the same size and type

The forces act in opposite directions

Question 3

What does networks third law state

Answer 3

“ for every action there is an equal and opposite reaction”

This means that forces always come in pairs

Question 4

What is a non-contact force

Answer 4

A force produced because an object is in a field

The objects don’t need to be touching for the force to act

Charges magnets and masses interact at a distance

Question 5

What are some non contact forces

Answer 5

Electrostatics

Magnetism

Gravity

Question 6

What is a field

Answer 6

A field is a region where an electrical charge a magnetic material or a mass experiences a force

Question 7

How do you represent forces

Answer 7

A force arrow

The length of the arrow shows the magnitude

The direction of the arrow shows the direction of force

Question 8

An object will deform a surface until the normal contact force balances the weight True or false

Answer 8

True

Question 9

What is a contact force

Answer 9

A force that only acts when objects are in contact

Question 10

What are examples of contact forces

Answer 10

Friction

Drag

Normal contact force

Upthrust

Tension

Question 11

What is an example of friction

Answer 11

Friction on a sliding box

Question 12

What is an example of drag

Answer 12

Drag on a falling leaf

Question 13

What is an example of normal contact force

Answer 13

Normal contact force acting on an elephant

Question 14

What is an example of upthrust

Answer 14

Upthrust on a floating boat

Question 15

What is an example of tension

Answer 15

Tension in the chord of a bungee jumper

Question 16

How does friction work

Answer 16

It occurs because the atoms that make up the surfaces interact when rough surfaces slide over each other

Question 17

What is drag

Answer 17

A force that acts opposite to the direction of the motion of the body

Question 18

How does drag work (in terms of particles)

Answer 18

The particles of the liquid or gas collide with the object and the object pushes them away

Question 19

How does normal contact force work

Answer 19

Solid objects deform slightly when you exert a force on them

The bonds between the particles are compressed

Question 20

How does upthrust work

Answer 20

Gravity produces pressure differences in a fluid

The pressure produces a net upwards force

Question 21

How does tension work

Answer 21

Solid objects deform slightly when you exert a force on them

The bonds between the particles are stretched

Question 22

What is a free body diagram

Answer 22

A free body diagram is a diagram that shows the forces acting on a single object

Question 23

Why do we use free body diagrams

Answer 23

We use them to predict or explain the motion of the object or to do calculations

Question 24

What is the resultant force

Answer 24

The force when two or more forces are added together as vectors

Question 25

What is the net force

Answer 25

the force when two or more forces are added together as vectors

Question 26

What is Newton’s First law?

Answer 26

“An object will continue to stay at rest or move with uniform velocity unless a force acts upon it”

This means it takes a resultant force to change the motion of an object

Question 27

What will happen to an object is the resultant force is 0

Answer 27

The speed or direction of an object will not change

Question 28

What is inertia

Answer 28

the measure of how difficult it is to change an object’s velocity

Question 29

Why do objects move at a steady speed

Answer 29

If the resultant force is 0 then the speed or direction of an object doesn’t change

A steady speed means there is 0 resultant force.

The object will continue to move with a steady velocity if there is no force acting on it

Question 30

What is equilibrium

Answer 30

An object is in equilibrium if the resultant force is 0

This means that the forces cancel out and the motion does not change

Question 31

What can a resultant force do?

Answer 31

Change the speed of an object

Change the direction of motion of an object

Change both the speed and direction of motion of an object

Question 32

What is Newton’s second law of motion

Answer 32

If the resultant force is not 0 the motion of an object changes

The acceleration that the resultant force produces depends on:
- the size of the resultant force

• the mass (inertia) of an object

Question 33

How do you calculate force

Answer 33

Force (N) = mass (kg) ✖️ acceleration (m/s2)

Question 34

1N = 1Kgm/s2

Answer 34

True

Question 35

What happens to the acceleration of an object when it is moving in a circle

Answer 35

An object moving in a circle at a constant speed is accelerating (even though the speed does not change)

It is constantly changing direction so it’s velocity is constantly changing

Question 36

What is terminal velocity?

Answer 36

The velocity that a moving object reaches when the resultant force is zero

Question 37

What happens in terms of motion when you skydive

Answer 37

When you jump out of the plane you accelerate and you motion changes because there is a resultant force on you

The air exerts a force (air resistance) on you but the air exerts a larger force (gravity)

As you accelerate the force of the air increases and equals the force of the earth on you so your motion doesn’t change

A parachute increases the force of the air to reduce your velocity.