Newtons Laws

Question 1

What is newtons 1st law?

Answer 1

The law of inertia
“A body continues in its state of rest or motion unless acted upon by a force

The greater the mass of an object,the more force (greater inertia) needed to move it

Eg. 8kg ball has a greater inertia because it’s large mass, therefore requires greater force to move it

Inertia- the amount of resistance to change an objects state of motion

Question 2

What is Newtons 2nd law?

Answer 2

Law of acceleration / momentum
“The rate of change of acceleration to a body is proportional to the force applied to it”

The greater the force applied to an object, the faster the acceleration will be

• small force = slow acceleration
• large force = fast acceleration

Acceleration = change in velocity / time

Question 3

Define momentum

Answer 3

Momentum = mass x velocity

• larger mass or larger velocity of object = increase in momentum
• object can only have momentum if moving
• greater the momentum, the more force needed to stop or slow object down

-eg. Rugby player runs at 9m/s mass= 100kg
100kg x 9m/s = momentum = 900kg m/s

Question 4

Define conservation of linear momentum

Answer 4

Total momentum of two objects before and after impact are equal

-momentum of one object is transferred on contact with other object,resulting in no change in momentum,rather a transfer of momentum

Eg. Swing of baseball bat towards ball, both ball &a bat passes certain amount of momentum before collision

Upon collision, ball e prides away while bat rapidly decelerates during follow through
Total momentum between objects has stayed the same, most momentum has been transferred into baseball to send flying away

Increasing momentum- large force, over small time
Decreasing momentum- small force, over long time

Question 5

Define impulse

Answer 5

Change in momentum of an object

Impulse = force x time over which force is applied

Longer force can be applied to an object, and the greater size of force applied, greater the objects impulse

Eg. a rugby scum = large force + long time = argue impulse
Eg. Tennis racquet
-loose strings- ball on racquet for longer
- more power, less control
-tighter strings- ball on racquet for less time
-less power, more control

Question 6

Newtons 3rd law

Answer 6

Law of action and reaction
“For every action, there is an equal opposition reaction”

When two objects act upon each other, forces are opposite in direction and equal in magnitude

• equal amount of force
• opposite direction of force

Eg. In backstroke, swimmer applies large force against wall, in return, applied equal and opposite force back in swimmer, allows to push off with greater force