Matter
The state of matter with a definite shape and definite volume
solid
What is kinetic energy?
energy of motion
What is the unit for energy?
What is the unit for work?
What is the unit for power?
energy & work = joule
power = watt
Increasing an object’s height increases what?
This state of matter takes the shape of its container but keeps a definite volume.
liquid
A moving bowling ball has more kinetic energy than a tennis ball moving at the same speed. Why?
bowling ball has more mass
You are pushing on a wall. How much work is being done?
ZERO
A 18N object falls from a height of 20 m. What is its potential energy before falling
360 J
phase change from a liquid to a gas.
evaporation (or vaporization)
A 10 kg backpack is lifted 5 meters above the ground. Calculate the gravitational potential energy.
10 x 9.8 x 5 = 490 J
A student pushes a box with 20 N of force for 5 m. Find the work done
20 x 5 = 100J
A worker pushes a 40 N box across the floor for 12 meters. It takes him 6 seconds. How much work is done? How much power is done?
work: 40 x 12 = 480 J
power: (30 x 12) / 6 = 80 W
Dry ice changes directly from solid carbon dioxide into gas through this process.
sublimation
A 4 kg bowling ball rolls at 3 m/s. Calculate the kinetic energy
.5 x 4 x 3^2 = 18J
A machine does 500 J of work in 10 seconds. Find the power.
500 / 10 = 50J
A student places an ice cube in a warm room. Describe the sequence of phase changes that occurs as the ice absorbs thermal energy and eventually becomes water vapor.
melting (solid ice --> liquid water) followed by evaporation (liquid water --> water vapor)