Speed, Momentum, Acceleration, Work, Power, and Potential Energy Practice Problems TEK I6A – describe the law of conservation of energy; and TEK I4A – calculate speed, momentum, acceleration, work, and power in systems such as in the human body, moving toys, and machines

1. A mechanic used a hydraulic lift to raise a 12,054 N car 1.89 m above the floor of a garage. It took 4.75 s to raise the car. What was the power output of the lift? A 489W B 1815W C 4796 D 30,294W   P=W/t W=Fd W=(12,054N)(1.89m)=22,782.06J P=(22,782.06J)/(4.75s)=4,796.2W Answer:C (Practice problem from TEA released TAKS Test)

2. The weight lifter used a force of 980 N to raise the barbell over her head in 5.21 seconds. Approximately how much work did she do in raising the barbell? F 380 J G 982 J H 2,000 J J 10,000 J W=Fd W=(980N)(2.04m)=1999.2J Answer: H (Practice problem from TEA released TAKS Test)

3. According to this graph, what was the bicycle’s acceleration between 6 and 10 seconds?   A 0.0m/s2 B 0.65m/s2 C 1.6m/s2 D 6.5m/s2 Answer: A (Practice problem from TEA released TAKS Test)

4. An ant crawled from Point A to Point B in 4. 0 seconds 4. An ant crawled from Point A to Point B in 4.0 seconds. To the nearest tenth, what was the ant’s speed in centimeters per second? Record and bubble in your answer on the answer document. V=d/t On the actual TAKS test the students would need to use the ruler on their formula chart to find the distance. (Practice problem from TEA released TAKS Test)

5. A car traveled 150 km in 2. 5 hours 5. A car traveled 150 km in 2.5 hours. What was its average speed in km per hour? Record and bubble in your answer on the answer document. V=d/t V=(150km)/(2.5hrs)=60km/hr Answer: 60 or 60.0 or 60.00 or 60.000 would all be counted correct! (Practice problem from TEA released TAKS Test)

6. A ball moving at 30 m/s has a momentum of 15 kg·m/s 6. A ball moving at 30 m/s has a momentum of 15 kg·m/s. The mass of the ball is — A 45 kg B 15 kg C 2.0 kg D 0.5 kg   p=mv (15kg•m/s)=m(30m/s) m=(15kg•m/s)/(30m/s)=0.5kg Answer: D (Practice problem from TEA released TAKS Test)

7. How much work is performed when a 50 kg crate is pushed 15 m with a force of 20 N? A 300J B 750J C 1,000J D 15,000J W=Fd W=(20N)(15m)=300J Answer: A (Practice problem from TEA released TAKS Test)

8. What is the potential energy of the rock? A 59,900 joules B 64,600 joules C 93, 100 joules D 121,600 joules PE=mgh PE=(95kg)(9.8m/s2)(100m)=93,100joules Answer: C (Practice problem from TEA released TAKS Test)