Momentum
What is the formula for Momentum? (Include the names of the units involved)
P = Mass x Velocity
What does the slope of a position-time graph represent?
Velocity
Which forces act horizontally and which act vertically? (On a flat surface)
Applied Force & Friction = Horizontal
Normal Force & Gravity = Vertical
What is Power?
The amount of energy transferred/converted per unit time
What is Newton’s 1st Law?
An object at rest will stay at rest unless acted upon an unbalanced force.
A truck moves along a frictionless road at a constant speed. A large load of gravel is then dumped onto the top of the truck. What happens to the velocity of the truck when the gravel is dumped onto it?
It decreases. (Because its total mass increased while momentum was conserved. In order for the total momentum to remain the same, the velocity of the truck must decrease.)
Kinematics is…
…the motion of objects
What is the upward force that acts on an object that is resting on a flat surface?
Normal Force (Fn)
Units of Power & Work
(W)Watts = Power
(J)Joules = Work
What is Inertia?
A 60 kg student at rest on a frictionless rink throws a 6 kg box, giving the box a velocity of 12 m/s. What is the initial velocity of the student after the box was thrown?
1.2 m/s backwards/-1.2 m/s
Vsf = (6kg)(12m/s)/60kg = -1.2 m/s
(Negative sign is the opposite direction of the ball’s velocity)
What does positive and negative velocity indicate?
Indicates the direction an object is moving.
When surfaces slide over each other a force of __ happens.
Friction
What are the formulas for Work & Power?
Work = F x D
Power = W/t OR F x V
If a 20kg object is moving at a constant speed, how much net force is required to keep it in motion?
0 Newtons
(Constant velocity = 0 acceleration)
A 5kg rifle is fired, with a .05 kg bullet leaving the barrel at 450 m/s. What is the final momentum of the bullet-gun system.
0
What is Negative Acceleration?
Slowing down in the positive direction and speeding up in the negative direction.
What is Equilibrium?
A state where opposing forces are balanced with no change in motion. (Net force = 0)
How is Work and Power related?
Power is the rate at which work is done or how fast it is transferred.
Two football players collide with each other while running at the same speed. The lighter player being knocked over by the heavier player is an example of which Newton’s Law?
2nd Law
What symbol represents angular momentum?
L
As an object speeds up while free falling, is it accelerating? If so, is it increasing, decreasing, or constant?
Yes, the object is accelerating. The acceleration during the free fall is constant and is caused by gravity.
A 1200kg car pulls a 500kg trailer along a leveled frictionless road. The car has an acceleration of 1.3 m/s2. What is the force exerted by the car on the trailer?
650N
If it takes 10 seconds to do 5000J of work, what is the power output?
500W
A crumpled piece of paper hits the ground before a flat sheet of paper because…
there is more air resistance against the flat paper than the crumpled one.