Work, Energy & Power
Q. If a 10 kg object is raised to a height of 5 m, what is the work done against gravity? (g = 9.8 m/s²)
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A.
490 J
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B.
980 J
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C.
150 J
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D.
250 J
Solution
Work = m * g * h = 10 kg * 9.8 m/s² * 5 m = 490 J.
Correct Answer: B — 980 J
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Q. If a 10 N force is applied at an angle of 60 degrees to the horizontal while moving an object 3 m, what is the work done? (2020)
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A.
15 J
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B.
30 J
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C.
25 J
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D.
5 J
Solution
Work done = Force × Distance × cos(θ) = 10 N × 3 m × cos(60°) = 10 N × 3 m × 0.5 = 15 J
Correct Answer: A — 15 J
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Q. If a 1000 kg car is moving at a speed of 15 m/s, what is its kinetic energy?
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A.
112,500 J
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B.
225,000 J
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C.
150,000 J
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D.
75,000 J
Solution
Kinetic Energy = 0.5 × mass × velocity² = 0.5 × 1000 kg × (15 m/s)² = 112,500 J
Correct Answer: B — 225,000 J
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Q. If a 1000 kg car is moving with a speed of 15 m/s, what is its kinetic energy?
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A.
112,500 J
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B.
225,000 J
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C.
75,000 J
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D.
150,000 J
Solution
Kinetic Energy = 0.5 × mass × velocity² = 0.5 × 1000 kg × (15 m/s)² = 112,500 J
Correct Answer: B — 225,000 J
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Q. If a 2 kg object is lifted to a height of 10 m, what is the potential energy gained by the object? (g = 9.8 m/s²)
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A.
19.6 J
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B.
98 J
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C.
39.2 J
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D.
78.4 J
Solution
Potential Energy (PE) = mgh = 2 kg × 9.8 m/s² × 10 m = 196 J.
Correct Answer: B — 98 J
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Q. If a 2 kg object is moving with a velocity of 15 m/s, what is its kinetic energy?
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A.
225 J
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B.
150 J
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C.
300 J
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D.
450 J
Solution
Kinetic Energy = 1/2 * m * v^2 = 1/2 * 2 kg * (15 m/s)^2 = 225 J.
Correct Answer: A — 225 J
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Q. If a 2 kg object is moving with a velocity of 3 m/s, what is its kinetic energy?
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A.
9 J
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B.
6 J
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C.
3 J
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D.
12 J
Solution
Kinetic Energy = 0.5 * m * v² = 0.5 * 2 kg * (3 m/s)² = 9 J.
Correct Answer: A — 9 J
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Q. If a 4 kg object is moving with a speed of 5 m/s, what is its kinetic energy?
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A.
50 J
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B.
40 J
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C.
100 J
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D.
80 J
Solution
Kinetic Energy (KE) = 0.5 × m × v² = 0.5 × 4 kg × (5 m/s)² = 0.5 × 4 × 25 = 50 J.
Correct Answer: D — 80 J
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Q. If a 5 kg object is dropped from a height of 10 m, what is its potential energy just before it hits the ground? (g = 9.8 m/s²)
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A.
490 J
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B.
980 J
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C.
245 J
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D.
2450 J
Solution
Potential Energy (PE) = m × g × h = 5 kg × 9.8 m/s² × 10 m = 490 J.
Correct Answer: B — 980 J
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Q. If a car accelerates from rest to a speed of 20 m/s, and its mass is 1000 kg, what is the kinetic energy of the car at that speed? (2020)
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A.
200 J
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B.
1000 J
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C.
2000 J
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D.
4000 J
Solution
Kinetic Energy = 0.5 × mass × velocity² = 0.5 × 1000 kg × (20 m/s)² = 200000 J = 2000 J
Correct Answer: C — 2000 J
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Q. If a car accelerates from rest to a speed of 20 m/s, what is the kinetic energy of the car if its mass is 1000 kg?
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A.
200,000 J
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B.
100,000 J
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C.
50,000 J
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D.
400,000 J
Solution
Kinetic Energy = 0.5 × mass × velocity² = 0.5 × 1000 kg × (20 m/s)² = 200,000 J
Correct Answer: B — 100,000 J
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Q. If a car with a mass of 1200 kg is moving at a speed of 15 m/s, what is its kinetic energy? (2021)
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A.
13500 J
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B.
9000 J
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C.
18000 J
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D.
27000 J
Solution
Kinetic Energy = 0.5 × mass × velocity² = 0.5 × 1200 kg × (15 m/s)² = 13500 J
Correct Answer: A — 13500 J
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Q. If a force of 20 N moves an object 5 m in the direction of the force, what is the work done?
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A.
100 J
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B.
50 J
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C.
20 J
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D.
200 J
Solution
Work = Force * Distance = 20 N * 5 m = 100 J.
Correct Answer: A — 100 J
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Q. If a person does 300 J of work in 15 seconds, what is their average power output?
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A.
20 W
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B.
15 W
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C.
25 W
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D.
30 W
Solution
Power = Work / Time = 300 J / 15 s = 20 W
Correct Answer: A — 20 W
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Q. If a person does 300 J of work in 15 seconds, what is their power output?
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A.
20 W
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B.
15 W
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C.
25 W
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D.
30 W
Solution
Power = Work / Time = 300 J / 15 s = 20 W
Correct Answer: A — 20 W
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Q. If a person lifts a 20 kg box to a height of 2 m, what is the work done against gravity? (g = 9.8 m/s²)
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A.
392 J
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B.
196 J
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C.
588 J
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D.
784 J
Solution
Work = m * g * h = 20 kg * 9.8 m/s² * 2 m = 392 J.
Correct Answer: B — 196 J
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Q. What is the power output of a motor that does 1200 J of work in 30 seconds?
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A.
20 W
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B.
40 W
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C.
60 W
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D.
80 W
Solution
Power = Work / Time = 1200 J / 30 s = 40 W.
Correct Answer: C — 60 W
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Q. What is the power output of a motor that does 3000 J of work in 15 seconds?
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A.
200 W
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B.
300 W
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C.
400 W
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D.
500 W
Solution
Power = Work / Time = 3000 J / 15 s = 200 W.
Correct Answer: B — 300 W
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Q. What is the work done when a 50 N force moves an object 3 m in the direction of the force?
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A.
150 J
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B.
100 J
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C.
50 J
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D.
200 J
Solution
Work done (W) = F × d = 50 N × 3 m = 150 J.
Correct Answer: A — 150 J
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Q. What is the work done when a force of 15 N moves an object 3 m at an angle of 0 degrees to the direction of motion?
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A.
45 J
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B.
30 J
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C.
60 J
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D.
75 J
Solution
Work = Force * Distance * cos(θ) = 15 N * 3 m * cos(0°) = 45 J.
Correct Answer: A — 45 J
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Q. What is the work done when a force of 15 N moves an object 4 m in the direction of the force?
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A.
60 J
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B.
30 J
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C.
45 J
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D.
75 J
Solution
Work done = Force × Distance = 15 N × 4 m = 60 J
Correct Answer: A — 60 J
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Showing 31 to 51 of 51 (2 Pages)
