Newton's Laws

Question 1

Newton’s first law states…

Answer 1

an object has constant velocity unless acted upon by a net force

Question 2

What is inertia?

Answer 2

the natural tendency of an object to maintain its velocity

• an object at rest wants to stay at rest
• a moving object wants to keep moving at the same velocity
• IS NOT A FORCE

Question 3

The ______ the mass, the _______ the inertia (fill the blanks)

Answer 3

larger, greater

Question 4

What is net force?

Answer 4

total force acting on an object

Question 5

What is the difference between balanced and unbalanced forces?

Answer 5

balanced:

• equal and opposite force acting on an object
• net force = 0
• either at constant velocity or rest

unbalanced:

• without equal and opposite force acting on an object
• net force = acceleration

Question 6

On Earth, what are the three forces that slow moving objects?

Answer 6

air resistance, water resistance, friction and gravity (increases friction forces)

Question 7

What is gravity?

Answer 7

the attractive force between two objects with mass

Question 8

How inertia affects people when their bodies accelerate sharply?

Answer 8

upwards: force acts on bones and flesh and blood’s inertia cause it to rush to your feet. brain doesn’t get enough oxygen, causing black out.
downwards: blood rushes to head and causes red out, when blood comes out of eyes, nose, ears and mouth

Question 9

Newton’s third law states…

Answer 9

every action has an equal and opposite reaction

Question 10

Name 5 characteristics of forces in Newton’s third law

Answer 10

• come in pairs
• equal in size
• opposite in direction
• act on different objects
• same type of force
• object A exerts a force on object B, so object B exerts a force on object A

Question 11

Are reaction forces balanced or unbalanced?

Answer 11

unbalanced, as the forces act on different objects

Question 12

The Moon’s gravitational pull on the Earth is ____________ the Earth’s gravitational pull on the Moon.

Answer 12

equal to

Question 13

Explain why forces have equal size.

Answer 13

object A and B are both 1kg. they have gravitational forces that are equal in size. if we add another 1kg mass to earth, the force on the moon doubles. but the force on the earth also doubles. this is because both 1 kg masses are attracted to the moon.

no matter the mass, the two forces on different objects are still equal in size.

Question 14

Net forces of the same size always/don’t always have the same effect

Answer 14

don’t always

Question 15

A net force has ____ effect on high mass objects and ____ on low mass objects

Answer 15

less, more

Question 16

difference between mass and weight

Answer 16

mass is the amount of matter in an object

weight is the force of gravity on an object

Question 17

Newton’s second law states…

Answer 17

the net force of an object is equal to its mass multiplied by its acceleration

Question 18

How to calculate acceleration in a graph?

Answer 18

rise/run

Question 19

What is the formula for Newton’s second law?

Answer 19

F = ma
—> can be rearranged as
m = F/a
a = F/m

Question 20

Which variables of Newton’s second law are related to each other?

Answer 20

acceleration is directly proportional to net force inversely proportional to mass

Question 21

What are the standard units for force, mass and acceleration?

Answer 21

f = newton
m = kg
a = m/s/s

Question 22

Why does it take more force to accelerate a greater mass?

Answer 22

net forces produce different accelerations on objects with different masses because they have different amounts of inertia

Question 23

What is a free body diagram and what does it help to do?

Answer 23

• a representation of all the forces acting on an object

- helps calculate the net force

Question 24

What is a contact force and name examples?

Answer 24

• a force that only occurs when objects touch

- e.g. friction, air and water resistance, applied forces and collision forces

Question 25

What is a non-contact force and name examples?

Answer 25

• a force that occurs when objects aren’t touching

- e.g. gravity, magnetism and electrostatic forces

Question 26

What is support force?

Answer 26

an upward force exerted on an object by a solid surface. it balances out gravity and prevents it from falling.

Question 27

What is reaction force?

Answer 27

the force that is paired with another force in newton’s third law of motion

Question 28

What is applied force?

Answer 28

a type of force exerted by an animal, person or machine