Work and Energy

1. Work and Energy

2. Not a type of energy: a) Chemical b) Electrical c) Mechanical d) Political

3. By definition, Mechanical Energy means “the energy required to:” • Boil water • Fix a car • Move an object • Heat a home

4. Two types of mechanical energy: • Nuclear and Electrical • Electrical and Kinetic • Kinetic and Gravitational • Thermal and Electrical

5. The General Equation for all Mechanical Work is: a) W = Fxd b) W = mgh c) W = ½ mv2 d) W = mg

6. Work can be done by: • Boiling water • Raising a book onto a shelf • Accelerating a mass • All of the above

7. I can do work by: • dropping a book. • Holding a heavy bag of groceries • Skateboarding at a constant speed. • Doing push-ups

8. I can do work by: • Writing a letter • Jogging to school • Climbing stairs • Building a fort

9. The Earth does work when: • I lift a book on to a shelf • I am tobogganing down a hill • I drive my car • I skate along the canal

10. A ramp has an IMA of 5. This means: • It takes a force of 5N to push a 1N weight up the ramp. • It takes a force of 1N to push a 5N weight up the ramp. • If it takes 5J of energy to lift an object without the ramp, it will only take 1J of energy using the ramp. • If it takes 1J of energy to lift an object without the ramp, it will take 5J of energy using the ramp.

11. A simple machine: • Allows us to do the same work with less energy. • Allows us to do the same work with more energy. • Allows us to do the same work with less force. • Allows us to do the same work with more force.

12. A frictionless pulley system has an IMA of 5. Which is True: • To lift a mass up 5m, I need to pull 1m of rope • To lift a mass up 1m, I need to pull 5m of rope • To lift a 1N weight, I need a force of 5N. • None of the above

13. A pulleys system has friction. Which of the following is FALSE: • The AMA of the system is less than the IMA of the system. • The efficiency of the system is less than 100% • It will take more force to lift the weight using the pulley system than without the pulley system. • It will take more energy to lift the weight using the pulley system than without the pulley system

14. To pull a nail out of a block of wood, you need a lever with a high MA because: • You need a lot of force to move a small mass. • The nail moves a greater distance than your hand does. • A small force from your hand will be converted into a larger force pulling the nail. • You want to pull the nail using less work.

15. This machine has an IMA less than 1.0: • Crowbar • Baseball bat • Ramp • Hole punch

16. Beaker tongs have an IMA of 1.0. The tongs are used because: • They allow us to grip the beaker without burning our fingers • They reduce the force on the beaker, making it less likely to break. • They increase the force on the beaker, making it less likely to slip. • They allow us to lift a heavy beaker with less force.

17. A machine has an efficiency of 80%. This means: • The machine is frictionless • The AMA is less than the IMA • The IMA is less than the AMA • Applied force is more than the load force

18. A skateboarder is gliding down a hill. Halfway down the hill, the total energy of the skateboarder is: • Eg • Ek • Ek + Eg • mcΔT

19. A skateboarder sits at rest atop a ramp. The speed of the skateboarder halfway down the ramp is calculated. The LOC of energy says: • Ek = Eg’ • Ek + Eg = Ek’ + Eg’ • Ek = Eg’ + Ek’ • Eg = Eg’ + Ek’