P2.2: Newton’s Laws

Question 1

What does Newtons first law state?

Answer 1

An object will remain stationary or at a constant velocity unless acted upon by an external force

Question 2

What does Newtons 2nd law state?

Answer 2

The force acting on an object is equal to its rate of change of momentum

Question 3

What formula is used to calculate the resultant force?

Answer 3

F = ma

Question 4

What is resultant force?

Answer 4

the overall force that acts on the object

Question 5

What happens if an object has zero resultant force?

Answer 5

It would remain stationary
OR
Maintain a constant velocity

Question 6

What does friction do?

Answer 6

Makes things slow down and stop

Question 7

How can you prevent friction from stopping you from moving?

Answer 7

Need a driving force to keep moving

Question 8

What happens when the driving force is equal to the friction force

Answer 8

Move at a steady speed

Question 9

What happens when the driving force is greater than the friction force

Answer 9

Object will accelerate

Question 10

What happens when the driving force is less than the friction force

Answer 10

Object will decelerate

Question 11

Where does friction occur?

Answer 11

Between 2 surfaces in contact

Question 12

When does drag occur?

Answer 12

When an object passes through a fluid
Boat and water

Question 13

What is an example of a type of drag?

Answer 13

Air resistance

Question 14

What happens to the resistance when te velocity of an object increases?

Answer 14

Resistance also increases

Question 15

How does an object reach terminal velocity?

Answer 15

When objects first set off, more driving force than friction: acceleration
As velocity and resistance increase, acceleration is reduced and until friction force is equal to driving force
Forces balanced - terminal velocity

Question 16

What is terminal velocity?

Answer 16

When friction forces are equal to the driving force and there are no resultant forces

Question 17

What is inertia?

Answer 17

The measure of how difficult it is to change an objects velocity

Question 18

What is inertia dependant on?

Answer 18

Mass - larger mass means larger intertia

Question 19

What does Newtons 3rd law state?

Answer 19

When two objects interact, the forces they exert on each other are equal and opposite

Question 20

How are mass momentum and velocity connected?

Answer 20

The greater the mass of an object and the greater the velocity, the more momentum an object has

Question 21

What equation links mass momentum and velocity?

Answer 21

Momentum (kg m/s) = mass (kg) x velocity (m/s)

Question 22

Is momentum a vector or scalar?

Answer 22

Vector - has size and direction

Question 23

What is momentum?

Answer 23

A measure of how hard it is to stop a moving object

Question 24

When pushing against a wall, the wall pushes back with an equal and opposite force.

This force is called:

Answer 24

The normal contact force

Question 25

The formula for momentum is:

Answer 25

p=mv

Question 27

How can acceleration change an objects momentum?

Answer 27

Velocity will increase which means the momentum is also increased

Question 28

If a hand pushed an object and changed its momentum, how could we calculate the force that the hand used to push the object?

Answer 28

If you calculate the change in momentum and divide it by the time in seconds. Answer given in newtons

Question 29

Why is it important that a car is built with seat belts, crumple zones and airbags in the scenario of a car crash?

Answer 29

If a car smashes into a wall for example, the momentum will almost instantly decrease to zero. This will cause a huge force exerted in the opposite direction towards anyone inside the car. This could cause the people to experience spinal injuries or head trauma. To reduce the chance of this, the change in momentum should be spread over a longer period of time to reduce the force. This gives a small amount of extra time for the car to lose momentum slower.

Question 30

Energy is never created or destroyed, it is only ever…

Answer 30

Transferred between different forms and objects

Question 31

What are examples of different transferred energy stores?

Answer 31

Thermal Gravitational potential Magnetic Elastic Kinetic Nuclear Electrostatic Chemical

Question 32

What is a system?

Answer 32

Particular object or groups of objects, the collection of the matter is known as a system

Question 33

When a force makes an object move…

Answer 33

Energy is transferred and work is done

Question 34

What is power?

Answer 34

The rate at which energy is transferred

Question 35

What is the formula for power?

Answer 35

Work done / time

Question 36

What is the formula for work done?

Answer 36

Force x distance

Question 37

What are the different ways energy can be transferred?

Answer 37

Mechanically Electrically Through heating Via infrared radiation Via light and sound waves

Question 38

What can an open system do?

Answer 38

Lorse or gain energy from the ‘outside world’

Question 39

What is one joule equivalent to?

Answer 39

One newton-metre