Q. A 10 kg object is dropped from a height of 20 m. What is its potential energy at the top? (2020)
-
A.
200 J
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B.
1000 J
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C.
1500 J
-
D.
3000 J
Solution
Potential Energy = mass × g × height = 10 kg × 10 m/s² × 20 m = 2000 J
Correct Answer: B — 1000 J
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Q. A 10 kg object is dropped from a height of 20 m. What is its potential energy at the top? (g = 9.8 m/s²) (1960)
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A.
196 J
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B.
98 J
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C.
294 J
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D.
490 J
Solution
Potential Energy (PE) = mgh = 10 kg × 9.8 m/s² × 20 m = 1960 J.
Correct Answer: C — 294 J
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Q. A 10 kg object is lifted to a height of 2 m. What is the work done against gravity? (g = 9.8 m/s²)
-
A.
196 J
-
B.
98 J
-
C.
20 J
-
D.
39.2 J
Solution
Work done (W) = m × g × h = 10 kg × 9.8 m/s² × 2 m = 196 J.
Correct Answer: A — 196 J
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Q. A 10 kg object is moving with a velocity of 4 m/s. What is its kinetic energy?
-
A.
80 J
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B.
40 J
-
C.
20 J
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D.
160 J
Solution
Kinetic Energy = 0.5 × mass × velocity² = 0.5 × 10 kg × (4 m/s)² = 80 J
Correct Answer: A — 80 J
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Q. A 10 kg object is thrown upwards with a velocity of 15 m/s. What is the maximum height it reaches? (g = 9.8 m/s²)
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A.
11.5 m
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B.
22.5 m
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C.
15.0 m
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D.
7.5 m
Solution
Using energy conservation: KE_initial = PE_max; 0.5 * m * v² = mgh; h = v² / (2g) = (15 m/s)² / (2 * 9.8 m/s²) = 11.5 m.
Correct Answer: A — 11.5 m
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Q. A 10 N force is applied to move an object 3 m. What is the work done if the force is applied at an angle of 60 degrees to the direction of motion?
-
A.
15 J
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B.
30 J
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C.
25 J
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D.
20 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. A 1000 kg car is moving at a speed of 15 m/s. What is its kinetic energy?
-
A.
112,500 J
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B.
75,000 J
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C.
50,000 J
-
D.
25,000 J
Solution
Kinetic Energy = 0.5 * m * v² = 0.5 * 1000 kg * (15 m/s)² = 112,500 J.
Correct Answer: A — 112,500 J
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Q. A 1000 kg car is moving at a speed of 36 km/h. What is its kinetic energy? (1 km/h = 1/3.6 m/s) (2000)
-
A.
500 J
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B.
1000 J
-
C.
2000 J
-
D.
5000 J
Solution
First convert speed: 36 km/h = 10 m/s. KE = 0.5 × m × v² = 0.5 × 1000 kg × (10 m/s)² = 0.5 × 1000 × 100 = 50000 J.
Correct Answer: C — 2000 J
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Q. A 1000 W electric motor runs for 2 hours. How much work does it do? (2023)
-
A.
720,000 J
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B.
1,000,000 J
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C.
2,000,000 J
-
D.
1,440,000 J
Solution
Work = Power × Time = 1000 W × (2 × 3600 s) = 7,200,000 J.
Correct Answer: D — 1,440,000 J
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Q. A 15 kg object is lifted to a height of 4 m. What is the work done against gravity? (g = 9.8 m/s²) (2021)
-
A.
588 J
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B.
5880 J
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C.
392 J
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D.
294 J
Solution
Work = mgh = 15 kg * 9.8 m/s² * 4 m = 588 J.
Correct Answer: A — 588 J
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Q. A 15 kg object is moving at a speed of 4 m/s. What is its kinetic energy?
-
A.
120 J
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B.
240 J
-
C.
480 J
-
D.
60 J
Solution
Kinetic Energy (KE) = 0.5 × m × v² = 0.5 × 15 kg × (4 m/s)² = 0.5 × 15 × 16 = 120 J.
Correct Answer: B — 240 J
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Q. A 1500 kg car accelerates from rest to a speed of 25 m/s. What is the work done on the car?
-
A.
468,750 J
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B.
375,000 J
-
C.
250,000 J
-
D.
187,500 J
Solution
Work done = Change in Kinetic Energy = 0.5 * m * v² = 0.5 * 1500 kg * (25 m/s)² = 468,750 J.
Correct Answer: A — 468,750 J
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Q. A 2 kg object is lifted to a height of 5 m. What is the potential energy gained by the object? (g = 9.8 m/s²)
-
A.
98 J
-
B.
19.6 J
-
C.
39.2 J
-
D.
49 J
Solution
Potential Energy = mass × g × height = 2 kg × 9.8 m/s² × 5 m = 98 J
Correct Answer: A — 98 J
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Q. A 2 kg object is lifted to a height of 5 m. What is the potential energy gained by the object? (2022)
-
A.
10 J
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B.
20 J
-
C.
30 J
-
D.
40 J
Solution
Potential Energy = mass × g × height = 2 kg × 10 m/s² × 5 m = 100 J
Correct Answer: B — 20 J
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Q. A 3 kg object is dropped from a height of 10 m. What is the potential energy at the top? (2022)
-
A.
30 J
-
B.
60 J
-
C.
90 J
-
D.
120 J
Solution
Potential Energy = mass × g × height = 3 kg × 10 m/s² × 10 m = 300 J
Correct Answer: C — 90 J
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Q. A 3 kg object is lifted to a height of 4 m. What is the work done against gravity? (g = 9.8 m/s²)
-
A.
117.6 J
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B.
29.4 J
-
C.
39.2 J
-
D.
78.4 J
Solution
Work done (W) = mgh = 3 kg × 9.8 m/s² × 4 m = 117.6 J.
Correct Answer: A — 117.6 J
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Q. A 4 kg object is lifted to a height of 2 m. What is the work done against gravity? (2022)
-
A.
40 J
-
B.
80 J
-
C.
20 J
-
D.
60 J
Solution
Work done = mass × g × height = 4 kg × 10 m/s² × 2 m = 80 J
Correct Answer: B — 80 J
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Q. A 5 kg object is dropped from a height of 10 m. What is its potential energy at the top? (g = 9.8 m/s²)
-
A.
490 J
-
B.
98 J
-
C.
50 J
-
D.
100 J
Solution
Potential Energy = mgh = 5 kg * 9.8 m/s² * 10 m = 490 J.
Correct Answer: A — 490 J
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Q. A 5 kg object is dropped from a height of 10 m. What is its speed just before it hits the ground? (g = 9.8 m/s²)
-
A.
14 m/s
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B.
20 m/s
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C.
10 m/s
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D.
15 m/s
Solution
Using energy conservation, Potential Energy = Kinetic Energy at the ground: mgh = 0.5mv²; v = √(2gh) = √(2 × 9.8 m/s² × 10 m) = 14 m/s
Correct Answer: A — 14 m/s
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Q. A block of mass 2 kg is lifted to a height of 5 m. What is the work done against gravity? (g = 9.8 m/s²)
-
A.
98 J
-
B.
196 J
-
C.
49 J
-
D.
20 J
Solution
Work done = mgh = 2 kg * 9.8 m/s² * 5 m = 98 J.
Correct Answer: B — 196 J
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Q. A car accelerates from rest to a speed of 20 m/s. If its mass is 1000 kg, what is the kinetic energy of the car at that speed?
-
A.
200,000 J
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B.
100,000 J
-
C.
50,000 J
-
D.
400,000 J
Solution
Kinetic Energy (KE) = 0.5 × m × v² = 0.5 × 1000 kg × (20 m/s)² = 0.5 × 1000 × 400 = 200,000 J.
Correct Answer: B — 100,000 J
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Q. A car accelerates from rest to a speed of 20 m/s. If its mass is 1000 kg, what is the kinetic energy of the car at this speed? (2000)
-
A.
200 J
-
B.
1000 J
-
C.
2000 J
-
D.
4000 J
Solution
Kinetic Energy (KE) = 0.5 × m × v² = 0.5 × 1000 kg × (20 m/s)² = 0.5 × 1000 × 400 = 200000 J.
Correct Answer: C — 2000 J
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Q. A car accelerates from rest to a speed of 20 m/s. If the mass of the car is 1000 kg, what is the kinetic energy of the car at that speed? (2000)
-
A.
200 J
-
B.
1000 J
-
C.
2000 J
-
D.
4000 J
Solution
Kinetic Energy (KE) = 0.5 × m × v² = 0.5 × 1000 kg × (20 m/s)² = 0.5 × 1000 × 400 = 200000 J.
Correct Answer: D — 4000 J
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Q. A car of mass 1000 kg accelerates from rest to a speed of 20 m/s. What is the kinetic energy gained?
-
A.
200,000 J
-
B.
100,000 J
-
C.
50,000 J
-
D.
20,000 J
Solution
Kinetic Energy = 0.5 * m * v² = 0.5 * 1000 kg * (20 m/s)² = 200,000 J.
Correct Answer: B — 100,000 J
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Q. A cyclist does 1500 J of work to climb a hill. If he takes 5 minutes, what is his average power output?
-
A.
5 W
-
B.
10 W
-
C.
15 W
-
D.
20 W
Solution
Power = Work / Time = 1500 J / (5 * 60 s) = 5 W.
Correct Answer: B — 10 W
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Q. A cyclist does 300 J of work to climb a hill. If the cyclist's mass is 75 kg, what is the height of the hill? (2023)
-
A.
0.4 m
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B.
0.5 m
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C.
0.6 m
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D.
0.8 m
Solution
Potential Energy = mass × g × height; 300 J = 75 kg × 10 m/s² × height; height = 300 J / (75 kg × 10 m/s²) = 0.4 m
Correct Answer: B — 0.5 m
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Q. A cyclist does 300 J of work to climb a hill. If the height of the hill is 5 m, what is the mass of the cyclist? (g = 9.8 m/s²)
-
A.
6.12 kg
-
B.
10 kg
-
C.
15 kg
-
D.
20 kg
Solution
Using Work = mgh; m = Work / (gh) = 300 J / (9.8 m/s² * 5 m) = 6.12 kg.
Correct Answer: A — 6.12 kg
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Q. A cyclist does 300 J of work to climb a hill. If the hill is 5 m high, what is the weight of the cyclist? (2020)
-
A.
60 kg
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B.
30 kg
-
C.
50 kg
-
D.
40 kg
Solution
Work = m × g × h. 300 J = m × 9.8 m/s² × 5 m. m = 300 J / (9.8 m/s² × 5 m) = 6.12 kg.
Correct Answer: A — 60 kg
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Q. A cyclist does 600 J of work to climb a hill. If he takes 30 seconds, what is his average power output? (2022)
-
A.
10 W
-
B.
20 W
-
C.
30 W
-
D.
40 W
Solution
Power = Work / Time = 600 J / 30 s = 20 W.
Correct Answer: B — 20 W
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Q. A cyclist is moving at a speed of 15 m/s. If the mass of the cyclist and the bicycle is 75 kg, what is the total kinetic energy?
-
A.
800 J
-
B.
900 J
-
C.
1000 J
-
D.
1200 J
Solution
KE = 0.5 × m × v² = 0.5 × 75 kg × (15 m/s)² = 0.5 × 75 × 225 = 8437.5 J.
Correct Answer: C — 1000 J
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