Burning fossil fuels for energy releases energy and carbon dioxide (greenhouse gas)
Define renewable resource
A renewable resource is a resource that either can be replenished in a short period of time or we will never run out of.
Define nonrenewable resource
A nonrenewable resource is a resource that either takes longer to replace than the speed in which we use or can never be replaced.
Assume a frictionless surface. If a block of wood has a force of 8N applied to the right and a force of 10N applied to the left. What is the resultant force?
8N to the right, 10N to the left gives a resultant of 2N to the left.
What are the eight forms of energy? What does the law of conservation of energy state?
Kinetic, Potential, Radiant, Nuclear, Sound, Thermal, Electrical, Chemical
Remember: Kinetic and Potential energy are sometimes referred to as Mechanical Energy
The law of conservation of energy states that energy cannot be created nor destroyed, it can only transform into other kinds. The amount of energy is constant.
Explain these Transfers:
A student plugs in a hair dryer. They turn it on and blow dries their hair.
Electrical energy --> mechanical energy --> thermal and sound energy.
The sun heats a solar panel, which is charging a batter.
Radiant energy --> chemical energy
A student walks to a window.
Chemical energy --> kinetic energy
Describe Newton's three laws of motion
1. Law of Inertia- an object in motion stays in motion, an object at rest stays at rest unless a force acts upon it
2. Law of Acceleration- the more force that is applied to a mass, the more that mass accelerates (F=MA)
3. Law of Action/Reaction- For any force that is applied to an object, there is an equal but opposite force unless the object moves.
How many simply machines are there? What are there?
There are six simple machines- Wheel-Axle, Lever, Screw, Wedge, Inclined Plane and Pulley
A bus is moving 26 m/s east. A ball is rolled to the back of the bus. The ball's velocity is 2m/s. What is the resultant velocity of the ball?
26m/s east - 2m/s west = 24m/s east
You push against a wall with a force of 20N. The wall doesn't move. What is the resultant force? How much did the wall push back on you? What law of motion is this an example of?
The forces are balanced, meaning the resultant force is 0. If the resultant force is 0, that means the force the wall is pushing back on you has to be the amount you're pushing on it, 20N. This is an example of the Law of Action/Reaction.
Gravity has a special number. What is that number?
G or g = 9.8m/s^2
A skydiver jumps out of an airplane. What is the skydiver's velocity after 10s?
The final velocity = g x t. So 9.8m/s^2 x 10s= 98m/s
You drop a penny off of a bridge. The penny takes 20 seconds to hit the water. What was its final velocity?
The final velocity = g x t. So 9.8m/s^2 x 20s = 196m/s
An object is traveling at 30km/hr. What is it's distance after 4 hours?
4 hours x 30km/hr = 120km
The same object now increases its speed to 40km. It took 5s to increase its speed. What is its acceleration?
a= change in velocity divided by change in time.
a = (40-30)/5 = 2m/s^2