P10 - Forces and Motion

Question 1

State Newton’s 2nd law.

Answer 1

• Directly proportional to the resultant force of an object
• Inversely proportional to the mass of an object

Question 2

What is an equation for force?

Answer 2

Force = mass x acceleration

Question 3

What is the unit for force?

Answer 3

Newton

Question 4

What is the unit for mass?

Answer 4

Kilograms - Kg

Question 5

What is the unit for acceleration ?

Answer 5

Meters per second squared

Question 6

What does inertia mean?

Answer 6

The tendency for an object to stay at rest or to continue in uniform motion(constant velocity) is called inertia.

Question 7

What does inertial mass refer to?

Answer 7

This refers to the measure of difficulty in changing an object’s velocity

Question 8

What does inertial mass mean?

Answer 8

An object with more mass has a greater tendency to resist a change in its moving state. More force is required to move a greater mass from rest.

Question 9

What is weight measured in ?

Answer 9

Newton

Question 10

What is the formula for weight?

Answer 10

Weight = mass x acceleration (due to gravity) W = mg

Question 11

What does terminal velocity mean?

Answer 11

The maximum velocity that an object can travel at in a fluid - liquid(water) and gas(air).

Question 12

What is stopping distance?

Answer 12

The distance it takes for a vehicle to stop. (Total stopping distance) = thinking distance + braking distance

Question 13

What is thinking distance?

Answer 13

The distance travelled in between the driver realising he needs to brake and actually braking / The distance travelled during the reaction time.

Question 14

What are factors affecting thinking distance? Give (3).

Answer 14

• How fast the car is going
• How intoxicated the person is(drinking/drugs)
• Concentration of the person (tiredness)
• Poor visability

Question 15

What are factors affecting breaking distance? Give (3)

Answer 15

• The speed of the vehicle.
• The mass of the vehicle.
• The condition of the brakes.
• The condition of the tyres(tread).
• The condition of the road( weather)

Question 16

What is the formula to calculate the breaking force?

Answer 16

a= v^2 - u^2 / 2s.

Question 17

How do you calculate momentum?

Answer 17

p (momentum)= m(mass) x v(velocity)

Question 18

What is meant by a closed system?

Answer 18

A physical system that does not exchange matter or energy with its surroundings.

Question 19

What is an elastic object?

Answer 19

An elastic object is one which regains its shape when the forces deforming it (e.g stretching or squashing) are removed.

Question 20

What happens when an elastic object is deformed?

Answer 20

When an elastic object is deformed the energy which caused it to deform is stored as elastic energy , whicn is released when the force is removed.

Question 21

What is compression?

Answer 21

When a force is exerted on an object.

Question 22

What is tension?

Answer 22

This happens when a force pulls on the object.

Question 23

What is Hook’s law?

Answer 23

The extension of a spring is directly proportional to the force applied, provided its limit of proportionality is not exceeded.

Question 24

What happens is a spring passes its limit of propotionality?

Answer 24

The material starts to behave in a non-linear way.
The material will no longer continue to deform and be able to regain its original shape.

Question 25

Give (3) features designed to reduce the impact felt.

Answer 25

Crumple zone Air bags Seat belt

Question 26

What is the equation for changing the momentum?

Answer 26

Force x time = Change in momentum

Question 27

What is pressure?

Answer 27

Pressure is the force per unit area

Question 29

What is the equation for pressure in liquids?

Answer 29

Pressure in liquids equation : p = p(density kg/m cubed) x h(m) x g(N/kg or m/s^2)

Question 30

What is the equation for pressure?

Answer 30

Pressure (Pa)= Force (N)/ Area (m squared)