Vocab
This type of energy is known as the energy associated with motion
What is kinetic energy
Running up the hill
Kinetic
You serve a volleyball with a mass of 5 kg. The ball leaves your hand at 20m/s. The ball has __________________ energy. Calculate it.
KE= 0.5(5)(20)^2
KE=1000 J
when an object is not moving but can still have energy
potential energy
A person sitting on a tree
Potential
There is a bell at the top of a tower that is 25m high. The bell weighs 135N. The bell has ___________________ energy. Calculate it.
ME=(135)(9.8)(25)
ME=33,075 J
How is mechanical energy calculated?
by adding potential energy and kinetic energy
Riding a bike down the street
kinetic
Three rocks are rolling down a hill at the same speed. Rock 1 has a mass of 1 kg; rock 2 has a mass of 1.5 kg, and rock 3 has a mass of 3 kg. Which rock has the most kinetic energy?
Rock 3
the energy possessed by an object due to its motion and position.
mechanical energy
Chemical bonds in sugar
potential
A 2 kg book has been dropped from the top of the football stadium. lt’s speed is 5 m/s when it is 3 meters above the ground. What is its mechanical energy?
ME= KE+ PE= 0.5(2)(5)^2 + (2)(9.8)(3)
25+58.8=83.8 J
the energy that is stored due to the height of an object from the ground
graviational potential energy
A child kicking a soccer ball
What is the mechanical energy of the cart on the right at position A. The cart is not in motion. (height=10 m, mass = 15 kg, gravity = 9.8 m/s2)?
ME=KE+PE
ME= 0+ (15)(9.8)(10)=1470 J