Work
The energy it takes to move/displace an object by a force in the same direction.
What is work?
The rate in which work is done over time.
What is power?
Energy cannot be created nor destroyed, but only transferred from one energy storage to another.
Ex: Kinetic energy and gravitational potential energy is converted to thermal energy.
What is the law of conservation of energy?
The momentum lost by an object in a closed system will be gained by other objects so that the total momentum will remain the same in the system.
What is the law of conservation of momentum?
If the mass of a car is doubled and the momentum remains the same, by what factor will the velocity change?
Hint: p = m*v
The velocity will decrease by a factor of 2 or be halved.
There are two requirements for work to be done.
What is force and displacement/distance?
The ability to do work.
What is energy?
A roller coaster cart has a total of 250 J of gravitational potential energy at the top of the ride. Find the kinetic energy when the roller coaster cart is at the bottom of the ride.
What is 250 J of kinetic energy?
Name the formula for an elastic (bouncy) collision.
What is m1v1i + m2v2i = m1v1f + m2v2f ?
The power of a motor remains the same. If the amount of work done is halved, how will the amount of time change?
Hint: P = W/t
The time will increase by a factor of two or doubles.
The formula for work.
What is W = F*d ?
There are three types of mechanical energy: gravitational potential energy, kinetic energy, and spring potential energy. Name the formulas.
What is GPE = m*g*h , KE = (1/2)*m*v2 ,
SPE = (1/2)*k*x2 ?
There is 34 J of kinetic energy and 54 J of gravitational potential energy. All of this energy is converted to 64 J of spring potential energy and _____ J of thermal energy.
What is 24 J of thermal energy?
Name the formula for an inelastic (sticky) collision.
What is m1v1i + m2v2i = (m1+m2)vf ?
The velocity of a car triples. If the mass of the car remains constant, how will this change the kinetic energy?
Hint: KE = (1/2)*m*v2
The kinetic energy will increase by a factor of 9.
It takes 85 J of kinetic energy to lift a couch. Find the amount of work done to lift the same couch.
What is 85 J of work done?
A 500 kg car takes a turn around the bend that requires 25,000 J of kinetic energy. Find the velocity of the car.
What is 10 m/s ?
A 0.02 kg pinball is shot from the machine at 3.0 m/s. The spring inside the machine is compressed 0.25 m. Find the spring constant.
HINT: SPE = KE
What is 2.88 N/m ?
Name the formula for an inelastic reverse (explosion) collision.
What is (m1+m2)vi = m1v1f + m2v2f ?
The force applied on a box is doubled and the amount of work done is tripled. How will this change the displacement/distance the box will move?
Hint: W = F*d
The displacement/distance will increase by a factor of 3/2.
It takes 16 J of work to be done to move a 3.5 kg box. Find how far the box moved.
HINT: F = m*g
What is 0.47 m?
A 4 kg ball is thrown 2 m up in the air in 5 s. Find the power it takes for the ball to be thrown up in the air.
What is 15.68 J/s or Watts?
An 80.0 kg man is riding a scooter down a ramp at 12 m/s. Find the height of the ramp.
Hint: g*h = (1/2)*v2
What is 7.3 m ?
A 450 kg train cart is moving at 8 m/s and couples with a 500 kg train cart that is at rest. Find the final velocity after the carts couple together.
What is 3.8 m/s ?
The amount of work done is doubled and the time has decreased by a half. How will this change the power?
Hint: P = W/t
The power will increase by a factor of 4 or quadrupled.