FA5.2 Conservation of Energy

Help with the Quizlette 5.2.1 .:. Help with the Quizlette 5.2.2

Help with P5.2

Get the assessment: FA05.2.docx

Get More Practice Problems: Worksheet-ConservationOfEnergy5.2.docx

The assessment solved:

Help with Quizlette 5.2.1 (pictures)

Front:

1. What is the speed at the bottom <Video>

2. What is the speed at the top? <Video>

3. What is the speed at the top? <Video>

Back:

4. What is the final velocity? <Video>

5. What force do the brakes exert? <Video>

6. What speed at the top <Video>

Help with Quizlette 5.2.2 (just words)

1 → 1 problems:

1) If you exert 15.0 N vertically upward a distance of 0.850 m on a 0.145 kg baseball, to what height above the starting point will it rise? Neglect friction, and assume the baseball was initially motionless. <Video>

2) A 2130 kg car coasts from rest down a small hill that is 2.40 m tall. What is the velocity of the car at the bottom? Neglect friction <Video>

3) A 0.440 kg hammer going 9.60 m/s horizontally strikes a nail, driving it into a wall 2.70 mm (0.00270 m) What force did it exert on the nail? <Video>

2 → 1 or 1 → 2 problems:

4) A 23.0 kg cart is going 5.70 m/s at the top of a 1.70 m tall hill. What speed does it have at the bottom? Neglect friction <Video>

5) A 53.0 kg cart already going 4.20 m/s is given a forward push with a force of 82.0 N for a distance of 11.0 m. It then rolls up a hill. To what height will it roll before stopping? Neglect friction <Video>

6) A 0.113 kg pine cone falls from a height of 5.60 m. It strikes the ground at 8.10 m/s. What was the average force of air friction slowing the pine cone as it fell? <Video>

2 → 2 problems:

7) A 12.0 kg cart is going 3.50 m/s on top of a 4.50 m tall hill. What is its speed on top of a 2.30 m tall hill? Neglect friction <Video>

8) A 26.0 kg kid sledding down a 2.70 m tall hill from rest gets a push of 78.0 N for 3.70 m. What is their speed when they are at an elevation of 1.10 m? Neglect friction <Video>

9) A 45.0 kg cart going 6.20 m/s on the top of a 4.10 m tall hill is slowed at the bottom with by a braking force over a distance of 2.30 m until it is going only 6.70 m/s. What is the braking force? <Video>

More Practice Problems:

Get this handout: Worksheet-ConservationOfEnergy5.2.docx

Conservation of Energy Questions from A5.2

1. a. A 0.145 kg baseball going 22.0 m/s straight up goes how high before stopping? FA5 2 #1a

b. A baseball pitcher speeds a 0.145 kg ball from rest to 38.0 m/s over a distance of 3.80 m. What must be the average force exerted on the ball? (Neglect friction or any change in elevation) FA5 2 #1b

c. A 1340 kg car is moving at some speed at an elevation of 5.50 m partway up a hill, and then coasts to a stop at an elevation of 12.0 m. How fast was it going at 5.50 m elevation? (Neglect friction) FA5 2 #1c

d. A 150. kg sled is going 3.40 m/s at the top of a 2.50 m tall hill. At the bottom it hits a patch of dirt that exerts a slowing force of 180. N for 4.20 m. How fast is the sled going after the dirt patch? (Neglect friction) FA5 2 #1d

2. a. A 0.320 kg hammer is going 8.20 m/s. What force would stop it in 0.120 m? FA5 2 #2a

b. A 1530 kg car starts at rest and rolls down a hill. At the bottom it is going 13.6 m/s. How high was the hill? (Neglect friction) FA5 2 #2b

c. Mom gives 55.0 kg Tamara a push from rest on her massless sled for a distance of 7.20 m at the top of a 3.80 m tall hill. If she is going 11.0 m/s at the bottom of the hill, what force did Mom exert at the top to speed her up? (Neglect friction) FA5 2 #2c

d. A 410. kg rollercoaster car going 3.40 m/s hits an accelerator that exerts a force of 780. N to speed up the car over a distance of 14.0 m. The car then rolls up a hill where it is going 4.20 m/s. What is the height of the hill? (Neglect friction) FA5 2 #2d

3. a. A 5.00 kg pendulum starts from rest 0.150 m above the lowest point. What is its speed when it reaches the lowest point? FA5 2 #3a

b. A 0.170 kg ball is sped up with a 5.00 N force straight up from rest a vertical distance of 3.50 m. To what height does it rise above its lowest point before stopping? (Neglect air friction) FA5 2 #3b

c. A 0.170 kg ball is sped up with a 5.00 N force straight up from rest a vertical distance of 3.50 m. What is the velocity of the ball when it is a height of 6.00 m above its lowest point? (Neglect friction) FA5 2 #3c

d. A 784 kg rollercoaster car is going 7.50 m/s at the top of a 2.15 m tall hill. At what height is it when it is going 4.50 m/s? (Neglect friction) FA5 2 #3d

4. a. What force over 0.180 m exerted on a 0.345 kg air track glider speeds it from rest to 1.21 m/s?

b. A 0.145 kg baseball is popped straight up, and goes 33.5 m in the air before coming back down. What was its initial velocity? (Neglect friction)

c. A 1370 kg car going 14.7 m/s on a level road strikes a puddle that exerts a retarding force of 5200. N What is the velocity of the car when it has gone 18.0 m into the puddle?

d. A 680. kg Rollercoaster car at rest on top of a 3.50 m tall hill is sped up by a force of 7780 N for a distance of 2.50 m. What is the height of the car when it is going 9.50 m/s (Neglect friction)

5. a. A 65.0 kg sled starts from rest at the top of a 4.40 m tall hill. What is its speed at the bottom of the hill? (Neglect friction)

b. Ferdinand exerts a force of 168 N for a distance of 18.5 m on the level speeding up a 1450 kg car initially at rest. The car then rolls up an incline. How much elevation will the car gain before it stops? (Neglect friction)

c. Reginald exerts a force of 195 N for a distance of 35.0 m on the level speeding up a 985 kg car from rest. The car then rolls up an incline. What elevation has the car gained when it has a velocity of 1.50 m/s? (Neglect friction)

d. A 450. kg roller coaster car initially at rest is launched from the top of a 2.30 m tall hill by a 4890 N force exerted over a distance of 3.80 m. What is the speed of the car when it is at the top of a 5.20 m tall hill? (Neglect friction)

The Instruction for this unit:

You should go through all the example problems...

6:35Conservation of Energy

Conservation of Energy Example 1

Conservation of Energy Example 2

Conservation of Energy Example 3