Force and mass determine acceleration
What is the acceleration of an object dependent on?
The size of the force applied and the mass of the object
How is force calculated?
Force = Mass x Acceleration
F=ma
You excitedly take your seat in NF class, thrilled to be learning physics. When you sit on the chair, the action force is your weight pushing down on the chair. What is the reaction force?
The chair pushing up on your body
What would happen if the ground you were standing on did not exert a reaction force back?
You would sink into the ground
Define variable
likely to change or be different
Which unit is force measured in?
Newtons
kg.m/s2
What causes an object to continue moving in a circle?
Centripetal force
If I know the force acting upon an object, what can I predict about that object?
The object's motion
I push on the wall, applying an action force of 5N. What is the reaction force?
5 N
Define contract
to become smaller or narrower
Two objects are pushed in a straight line with the same force. Object A has a mass of 10kg, while Object B has a mass of 20kg. Which is true of object A?
A- It will have greater acceleration
B- It will have less acceleration
C- It will have greater centripetal force
D- it will have less centripetal force
A- It will have greater acceleration
What would happen to acceleration if I applied a greater centripetal force to an object?
Acceleration would increase/ be greater.
What is the difference between balanced forces ( 1st Law) and action reaction pairs (3rd law) ?
Balanced forces act upon single objects, where as action/reaction pairs at on two different objects.
What is Newton's 3rd law of motion?
When one object exerts a force on another object, the 2nd object exerts and equal and opposite force on the 1st object.
Every action has an equal and opposite reaction.
Define massive
very large, solid, or heavy
How can an object accelerate when its speed does not change?
It's direction changes.
According to Newton's 2nd law of motion, what must happen in order to increase acceleration?
A- Inertia must increase
B- Force must increase
C- Force must decrease
D- Mass must increase
B- Force must increase
When you bang your toe into the leg of a table , the same amount of force that you exert on the table is exerted back on to your toe. Which best describes this situation?
A- Inertia
B- Motion
C- Balanced forces
D- action/reaction force pair
D- action/reaction force pair
Two people are having a tug of war. They are both pulling on the rope with the same amount of force? What would be the motion of the rope?
It will not move, as they are both exerting the same force
Define balanced
having good or equal amounts of all the necessary parts of something
Mr. Phillip is trying to workout how much force (thrust) his rocket needs to get him off the earth and heading towards the Moon.
His rocket while full of fuel has a mass of 500,000 kg
He wants the rocket to accelerate at 10 m/s2
How much force do his engines need to produce?
500,000 kg x 10 m/s2 = 5,000,000 kg.m/s2 or 5,000,000 N
or 5,000 Kn
To put this in perspective, the Saturn V rockets engines produced around 35,000 Kn of thrust at launch, while the rocket's mas was 2.8 million kilograms.
Mr. Phillip has launched his space rocket on a trip to the Moon. As the rocket gets closer to space, and burns off fuel, its acceleration starts to increase. Why?
As the rocket burns fuel, it's mass decreases.
As acceleration = force รท mass , as mass decreases acceleration increases
Using Newton's third law, describe how a jellyfish moves.
It squeezes water out of it's body, applying a force downwards. The water around the Jellyfish exerts the same force back, meaning the jellyfish moves upwards.
How can knowing all of Newton's laws of motion help you to win a canoe race?
You realize that you need to apply a large enough force to overcome the canoe's inertia. Having a smaller canoe with less mass would mean less inertia, so a smaller force is needed. Less mass would also result in greater acceleration.
Define exhaust
the gas produced when an engine is working