Work, Work, Work, Work, Work
The unit for work is the ___.
Joule
In a race, two cars have the same mass but different velocities. The car with the slower velocity has ___ kinetic energy than the other car does.
less
Electric blanket
Converts energy from __ to __.
electrical to thermal
The amount of work done in a certain time is…
Power
Energy in motion is known as…
You move a cart of pumpkins 15 m. This requires a force of 65 N. How much work was done while moving the pumpkin?
975 J = (65N)(15m)
How much energy does a 4 kg apple have that is thrown at a speed of 2 m/s?
8 J = (1/2)(4kg)(2m/s)^2
Windmill
Converts from __ to __.
mechanical (or kinetic) to electrical
How much power is used if a 100 J of work is done to move a box in 10 s?
10 watts = (100J)/10s
A 0.9 kg pineapple falls from a tree that is 5.8 m tall. How much energy does the pineapple have?
51.2 J = (0.9kg)(9.8m/s2)(5.8m)
The two conditions that must be met in order for work to be done.
1. Object must move.
2. Force must be applied in direction of motion.
List the type of potential energy each object below has.
A.Sandwich
B.Trampoline
A. Chemical potential energy
B. Elastic potential energy
fireworks
Converts from __ to __.
chemical to sound (or radiant or thermal)
How long would it take to do 36 J of work if 4 W of power are available?
9 seconds = (36J)/4W
How much heat is needed to warm 0.098 kg of gold from 15°C to 30°C if gold has a specific heat capacity of 136 J/kg°C?
199.9 J = (0.098kg)(136J/kgoC)(30oC-15oC)
A small child weighs 25 N. If they do a somersault and move a distance of 3 m, how much work was done?
75 J = (25N)(3m)
How much potential energy does a bird have that weighs 9 N and is sitting on a branch 3 m high?
27 J = (9N)(3m)
an apple falling off a tree limb
Converts from __ to __.
gravitational potential to kinetic
How much power is used if a force of 70 N is used to push a box a distance of 20 m in 5 s?
280 watts = (70N)(20m)/5s
Define thermal energy and mechanical energy.
thermal energy = KE + CPE
mechanical energy = KE + GPE
How far did you push a 12 kg barrel of tools if you did 276 J of work and pushed at a rate of 3 m/s2?
7.7 m = (276J)/12kg/3m/s2
What is the mass of a picture that falls off a shelf 6 m high and has 150 J of energy?
2.6 kg = (150J)/6m/9.8m/s2
A man eating dinner then tap dancing
Converts from __ to __ to __.
chemical to kinetic to sound
A motorcycle and its rider have a mass of 28 kg. If the cart accelerates at 6 m/s2 during a 40 m sprint in 100 s, how much power did the cart have?
67.2 watts = (28kg)(6m/s2)(40m)/100s
What is the mass of a ball that is rolling with a speed of 26 m/s and has 1,200 J of energy?
3.6 kg = (1200J)/0.5/(26m/s)^2