newton’slaws,pe&ke&energyconversions review) ·...
TRANSCRIPT
Newton’s Laws, PE & KE & Energy Conversions Review
1. Karen wants to place a ball on an inclined plane where it will have the most potenAal energy. Where on the inclined plane will she place the ball? Answer A
2. If Karen places the ball at the top of the inclined plane and releases it at what point will it have the greatest kineAc energy? Answer D
3. What happens to the kineAc energy and gravitaAonal potenAal energy of a ball in free fall? KE increases, PE decreases
4. In which situaAon will kineAc energy be changed to potenAal energy. a. A ball rolls to the boMom of an inclined plane.
b. A roller coaster slows down as it climbs up a hill. Answer B
5. In the roller coaster diagram above, at which point would the potenAal energy of the cart be the lowest? _____A______ the highest? ______B______
6. At which point would the kineAc energy of the cart be the
lowest? ______B______ the highest? ________A_______
7. Rank the leMers above from the locaAon of lowest potenAal energy to the locaAon of highest potenAal energy.
A, D, C, B
8. Which of the following systems has kineAc energy? I. Water flowing down a hill II. A ball rolling along the floor III. Atoms inside a rock which is siUng on a cliff
Answer: all the above 9. What is the energy conversion that happens
when a car burns gasoline? Answer: Chemical to mechanical
10. An object has 12.4 J of potenAal energy and 23.5 J of kineAc energy. What is the mechanical energy of the system? 12.4 J + 23.5 J = 35.9 J
11. What is the kineAc energy of an 9 kg bowling ball rolling at 3.30 m/s? KE = m(v2)/2 9(3.3)squared/2 =
49.005 J 12.When riding in a car, you will lean toward the right
when the car makes a leb turn. Which of Newton’s Laws does this demonstrate?
Newton’s 1st Law
13. Which spring will have the least elasAc potenAal energy? _____A___
14. Which spring will have the most elasAc potenAal energy? _______D_____
15. A sobball is thrown with 145 joules of energy. If the ball is moving at 20.0 m/s, what is the mass of the ball in kg? (Round the answer to the nearest hundredth.)
KE = m(v squared)/2 m(20 squared)/2 = 145J m 200/200 = 145/200 m = .725 Kg
16. What is the difference between velocity and speed? Velocity includes magnitude and direcAon. Speed only magnitude
• Write Newton’s three laws below: 1st -‐ Law of InerAa – object in moAon stays in moAon etc.
2nd-‐ Force = mass x acceleraAon object accelerates in the direcAon of the force
3rd-‐ acAon -‐ reacAon
4.What is the formula for calculaAng momentum? P = m v
5. Tim is playing pool. He causes the .19 kg ball
to move at 10.2 m/s. What is the momentum of the ball? P = m v .19kg x 10.2 m/s = 1.938 kg m/s
6. A man has a mass of 71.0 kg. What is his weight on the Earth? F = m a 71kg x 9.8m/s/s = 695.8 N
• A toy car starts from the rest posiAon and then a force is applied to it, causing it to move to the right as shown in the picture above.
9. What type of force is being applied to the car? Unbalanced force
10. In which direcAon will it travel? To the right
16. A 0.8 kg toy car is aMached to a spring scale. It is then pulled across a table. Using the spring scale measurement above, what is the acceleraAon of the toy car? A = F/m 4N/0.8 kg = 5 m/s/s
Which of the two objects paired below would have the greatest gravitaAonal aMracAon if the were 2.0 km apart? Answer is C
A
B
C