13 Laws of Motion and Momentum Flashcards
(25 cards)
what is newton’s 1st law of motion?
if there is no resultant force acting on an object, the object will remain at a constant velocity
what is newton’s 2nd law of motion?
Force is directly proportional to the rate of change of momentum and the change in momentum takes place in the same direction as the force.
what is newton’s 3rd law of motion?
When body A exerts a force on body B, body B exerts a force of equal magnitude and opposite direction on body A.
In terms of Newton’s third law describe the forces involved when a man stands on the floor.
The man is pulled towards the floor. The man pulls the floor towards him. These forces are equal in magnitude but are in opposite directions
what are some subtleties of newton’s 3rd law?
- the force pair are always the same type
- each force in the pair acts on only one of two objects (NEVER both forces on same object)
What two sets of units can be used for momentum?
Ns OR kgms⁻¹
How is the momentum of an object calculated?
mass x velocity
What is the principle of conservation of momentum?
The total momentum in a system of interacting objects is constant provided no external force acts
What is an elastic collision?
A collision in which kinetic energy is conserve
What is an inelastic collision?
A collision in which some kinetic energy is transferred to other forms
How is impulse calculated?
Force × time
What is the relationship between impulse and momentum?
Impulse is equal to change in momentum.
What is represented by the area under a force time graph?
Impulse
What is represented by the gradient of a momentum-time graph?
Resultant force
What is the change in momentum when an object of momentum p collides elastically at right angles with a wall?
-2p
When can F=ma be used?
When an object has constant mass.
Newtons first law states that if no external force is applied to an object, it will remain at rest or continue travelling at a constant velocity. true or false?
true
an object will experience acceleration if its speed remains constant but its direction changes. true or false?
true
if a student pushes a wall with a force of 150N, the wall will push back with a force of 150N directed in the opposite direction. true or false?
true
an applied force is proportional to the velocity of an object. true or false?
false
a footballer kicks a 430g football. the football was travelling at 21m/s before being kicked. after being kicked it leaves the footballer’s foot at 29m/s. what is the value for the impulse of the force on the football?
3.4Ns
what is the formula for force of tension?
T = mg + ma
NOTE:
mgh = 1/2 x m x v^2
what is change in momentum formula?
(mass x final velocity) - (mass x initial velocity) = change in momentum
