Vocab
the product of force and distance
What is work?
What does work require?
Force and displacement to be parallel.
A 7 kg object is motionless. Calculate kinetic energy.
0 J
A 500 kg roller coaster is traveling 7 m/s at a height of 25 m. Calculate mechanical energy.
134750 J
A 2,500 kg race car accelerates from rest to 35 m/s in 7.3 s. What is the power output of the engine?
209,760 W or 210 kW
Energy stored in a compressed object.
What is elastic potential energy?
Work is positive when...
The force and displacement are in the same direction.
True
A 2.1 kg rock is being held at a height of 8.7 m. Calculate it's kinetic energy just before hitting the ground.
179 J
Kyle is pushing his physics book away from him across the table. Is work being done?
Yes
Stored energy is known as
What is potential energy?
What is mechanical energy?
A spring with a spring constant of 125 N/m is stretched to 1.7 m. Calculate its elastic potential energy if its rest position is 1.3 m.
10 J
A 1500 kg car is being pushed down a road at a speed of 1.4 m/s. How much work must be done to increase the speed to 1.9 m/s
1237.5 J
rate of doing work
what is power?
True or False. (Assume masses are equal.) You and me both lug our books up a flight of steps. You get up there in 1 minute while it takes me 1.5 minutes. I am more powerful than you.
False
Energy of motion
What is kinetic energy?
Erin is lifting a 7 kg bowling ball up from the 2nd floor to the third from over the railing a distance of 2.5 meters. What is the work done?
171.5 Joules
Peter is setting a box down on the floor. Is work being done?
Yes, negative work.
A unit of power which equals to one joule per second
The Watt?
If the force applied to an object that is moved is quadrupled but moved for half the original distance, what happens to the work done?
Twice the Work
A 2.9 kg object has 656 J of kinetic energy. Calculate velocity.
21.3 m/s
Steph is carrying her book across the room by balancing the book steady on her hand. Is work being done?
No