Work
Do work on an object in the room
Move an object in the room so it has more potential energy
[compress a spring or move an object higher]
Move an object in the room and describe when it does and doesn't have kinetic energy
[object has kinetic energy only when it is moving]
True or False: Mechanical energy refers to the energy exerted by machines
False
True or False: Power refers solely to the amount of force something can exert
False
What is the definition of work?
The product of a component of a force and the displacement caused by that force
What is the definition of gravitational potential energy?
Energy associated with an object's position relative to a gravitational source
What is the definition of kinetic energy?
Energy associated with the motion of an object
What is the definition of mechanical energy?
The sum of kinetic and potential energy
A tennis ball and a bowling ball are both rolling along the ground at the same speed. Which has more kinetic energy and why?
The bowling ball because it is more massive
A worker holds a bucket above her head for ten minutes. Is this work?
No- there is no displacement
What is the definition of elastic potential energy?
Energy associated with an object being compressed or stretched
A net work of -40 J is done on an object. What is the change in its kinetic energy?
-40 J
Move an object in the room vertically in some way and describe what kinds of mechanical energy it has throughout its movement.
[depends on movement]
Define "power" in physics
Power is the rate at which work is done
A skateboard is moving north. One person pushes south on the board, doing 15 J of work, while another pushed north doing 30 J. Does the skateboard speed up or slow down?
It speeds up
What is a zero level?
The position relative to which an object is considered to have no gravitational potential energy
What is the work-kinetic energy theorem?
The net work done on an object is equal to the change in that object's kinetic energy
Is mechanical energy conserved in the presence of friction?
No
Yes, because the force you exerted had a component in the direction of your friend's displacement- it was not perpendicular.
A skateboard is moving north. One person pushes south on the board, doing 15 J of work, while another pushed north doing 30 J. What is the net work done?
The net work is 15 J.
A cup of coffee is sitting on a desk. A worker walks by and accidentally knocks the coffee cup to the floor. Has the coffee cup gained or lost potential energy? What kind?
It has lost gravitational potential energy
A skateboard is moving north. One person pushes south on the board, doing 15 J of work, while another pushed north doing 30 J. What is the change in kinetic energy of the skateboard?
The skateboard gains 15 J of kinetic energy.
Name one type of energy that is NOT mechanical
Electrical, chemical, etc.
A car starts to speed up as the driver presses on the gas pedal. Is the car experiencing positive or negative net work and is its change in kinetic energy positive or negative?
It is experiencing a positive net work and its change in kinetic energy is also positive