1st semester review_ Unit 3 and 4 --- Answer Key (2).docx - Name Answer Key Date Period st Physical Science 1 semester Final Exam Review Unit 3(Work

# 1st semester review_ Unit 3 and 4 --- Answer Key (2).docx -...

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Name: Answer Key Date: ______________ Period:_______ Physical Science 1 st semester Final Exam Review Unit 3 (Work, Power, & Machines) and Unit 4 (Energy & Heat) 1. Work (write yes or no to indicate if work is done in the following situations) a. Lifting a book YES c. Pushing a shopping cart YES e. pushing on a wall YES b. Carrying a book to your desk NO d. Holding weights over your head NO f. kicking a ball NO 2. Work problems (SHOW WORK) a. How much work is done if 25 N of force is used to move a rock 5 m? F = 25 N W = F * d 25N * 5m = 125 J d = 5 m b. How high did you lift your 12 N sister if you did 48 J of work? W = 48 J d = W/F 48J/12N = 4 m F = 12 N c. If 70 J of work is needed to move an object 15 m what is its weight (force)? W = 70 J F = W/d 70J/15m = 4.67 N d = 15 m 3.What can a machine multiply? A machine can multiply force. 4. Mechanical Advantage problems (SHOW WORK) a. What is the mechanical advantage of a lever if you apply 14 N of force to lift a car that weighs 1400 N? Input Force = 14 N MA = F R /F E 1400N/14N = 100 Output Force = 1400 N b. What is the mechanical advantage of a ramp that is 250 m long and 50 m high?

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