Forces

Question 1

What is a vector quantity?

Answer 1

A vector quantity is a quantity that has size and direction

Question 2

What is a scalar quantity?

Answer 2

A scalar quantity is a quantity that has size

Question 3

What are the examples of vector quantities?

Answer 3

Examples of vector quantities include force, velocity, displacement, acceleration, momentum

Question 4

What are the examples of scalar quantities?

Answer 4

Examples of scalar quantities include speed, distance, mass, temperature, time

Question 5

What are examples of contact forces?

Answer 5

Examples of contact forces include friction, air resistance, tension and normal contact force

Question 6

What are examples of non-contact forces?

Answer 6

Examples of non-contact forces include gravitational, electrostatic and magnetic

Question 7

How is a vector quantity represented in a diagram?

Answer 7

In a diagram, vector quantities are represented by an arrow, where the length shows the size and the direction of the arrow shows the direction by which the object is moving`

Question 8

What is it called when the resultant force is zero?

Answer 8

When the resultant force is zero, that means an object is in equillibrium

Question 9

How do you work out the resultant force of an object when the arrows are in opposite directions?

Answer 9

When the arrows of an object are in opposite directions, you take the smallest quantity from the biggest quantity

Question 10

How do you work out the resultant force of an object when the arrows are not facing opposite directions (eg one faces north and the other faces west)

Answer 10

To figure out the resultant force of an object when the arrows are not in opposite directions eg north and west, you draw an arrow from the centre outwards to the point where they meet and measure that arrow with a ruler. The measurement (eg 13cm) is the resultant force (so it would be 13N)

Question 11

What is Newton’s first law?

Answer 11

Newton’s first law is that if resultant force acting on an object is zero, it will remain stationery.

Question 12

What does Newton’s first law say about moving objects?

Answer 12

If resultant force acting on a moving object is zero, the object will continue to move in the same direction at the same speed

Question 13

What is the resultant force?

Answer 13

Resultant force is a force that causes speed and direction of an object to change

Question 14

What is Newton’s second law?

Answer 14

Newton’s second law states that the acceleration of an object is proportional to the resultant force acting on the object and inversely proportional to the mass of the object

Question 15

How does mass affect acceleration?

Answer 15

Larger mass = smaller acceleration

Smaller mass = Larger acceleration

Question 16

How does reultant force affect acceleration?

Answer 16

Greater resultant force = greater acceleration

Question 17

What is intertia?

Answer 17

Intertia is a resistance to a change in motion

Question 18

What does inertia depend on?

Answer 18

Inertia depends on it mass

Question 19

How does mass affect inertia?

Answer 19

Greater mass = more inertia. A greater resultant force is needed

Question 20

What is inertial mass?

Answer 20

Inertial mass is a measure of how difficult it is to change the velocity of an object

Question 21

What is Newton’s third law?

Answer 21

Newton’s third law is that whenever two objects interact, the forces they exert on each other are equal and opposite eg equal in magnitude, opposite in direction

Question 22

Describe the forces that act on a skydiver when they jump out of a plane (5)

Answer 22

1) . Weight acts as the only force when jumping out of the plane due to gravity. This will not change.
2) . Due to weight, the skydiver experiences force acting downwards, meaning they accelerate towards the ground.
3) . Skydiver experiences air resistance which acts upwards.
4) . Their air resistance increases as their velocity increases which eventually balances - no resultant force. The skydiver has reached terminal velocity.
5) . They open their parachute to increase the surface area so air resistance increases meaning resultant force then acts upwards. Velocity decreases meaning there is no resultant force and they land safely.

Question 23

What is the momentum of an object that is not moving?

Answer 23

An object that isn’t moving has no momentum

Question 24

What is conservation of momentum?

Answer 24

Conservation of momentum = in a closed system, the total momentum before an event is equal to the total momentum after an event

Question 25

How do you calculate momentum?

Answer 25

Momentum = mass x velocity

Question 26

How can we reduce the danger from a rapid change in momentum?

Answer 26

We can reduce the danger from a rapid change in momentum by making the change in momentum happen over a longer time

Question 27

What are the safety devices that slow momentum change?

Answer 27

Safety devices that slow momentum change include airbags, seatbelts, bike helmets, cushioned surfaces and crash mats