Work, Energy & Power: Essential Concepts for Exam Success

Work, Energy & Power

Q. How much work is done when a force of 10 N moves an object 5 m in the direction of the force?

A. 25 J
B. 50 J
C. 75 J
D. 100 J

Solution

Work = Force * Distance = 10 N * 5 m = 50 J.

Correct Answer: B — 50 J

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Q. How much work is done when a force of 15 N moves an object 3 m in the direction of the force?

A. 45 J
B. 30 J
C. 15 J
D. 60 J

Solution

Work done = Force × Distance = 15 N × 3 m = 45 J

Correct Answer: A — 45 J

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Q. How much work is done when a force of 30 N moves an object 4 m in the direction of the force?

A. 120 J
B. 90 J
C. 60 J
D. 30 J

Solution

Work = Force * Distance = 30 N * 4 m = 120 J.

Correct Answer: A — 120 J

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Q. If a 10 kg object is moving with a speed of 2 m/s, what is its kinetic energy?

A. 10 J
B. 20 J
C. 40 J
D. 80 J

Solution

KE = 0.5 × m × v² = 0.5 × 10 kg × (2 m/s)² = 0.5 × 10 × 4 = 20 J.

Correct Answer: B — 20 J

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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)

A. 490 J
B. 980 J
C. 150 J
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)

A. 15 J
B. 30 J
C. 25 J
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 10 N force is applied at an angle of 60 degrees to the horizontal while moving an object 4 m, what is the work done? (2020)

A. 20 J
B. 40 J
C. 30 J
D. 50 J

Solution

Work done = Force × Distance × cos(θ) = 10 N × 4 m × cos(60°) = 10 N × 4 m × 0.5 = 20 J

Correct Answer: C — 30 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?

A. 112,500 J
B. 225,000 J
C. 150,000 J
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?

A. 112,500 J
B. 225,000 J
C. 75,000 J
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 1000 W motor runs for 2 hours, how much work does it do? (2000)

A. 7200 J
B. 2000 J
C. 3600000 J
D. 100000 J

Solution

Work = Power × Time = 1000 W × (2 hours × 3600 s/hour) = 1000 W × 7200 s = 7200000 J

Correct Answer: C — 3600000 J

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Q. If a 1500 kg car is moving at a speed of 30 m/s, what is its kinetic energy?

A. 675,000 J
B. 450,000 J
C. 225,000 J
D. 900,000 J

Solution

Kinetic Energy = 0.5 × mass × velocity² = 0.5 × 1500 kg × (30 m/s)² = 675,000 J

Correct Answer: B — 450,000 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)

A. 19.6 J
B. 98 J
C. 39.2 J
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 lifted to a height of 3 m, what is the potential energy gained by the object? (g = 9.8 m/s²)

A. 58.8 J
B. 19.6 J
C. 29.4 J
D. 39.2 J

Solution

Potential Energy (PE) = mgh = 2 kg × 9.8 m/s² × 3 m = 58.8 J.

Correct Answer: A — 58.8 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?

A. 225 J
B. 150 J
C. 300 J
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?

A. 9 J
B. 6 J
C. 3 J
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 3 kg object is moving with a speed of 4 m/s, what is its kinetic energy?

A. 12 J
B. 24 J
C. 36 J
D. 48 J

Solution

KE = 0.5 × m × v² = 0.5 × 3 kg × (4 m/s)² = 0.5 × 3 × 16 = 24 J.

Correct Answer: B — 24 J

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Q. If a 4 kg object is lifted to a height of 2 m, what is the work done against gravity? (2021)

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. If a 4 kg object is moving with a speed of 5 m/s, what is its kinetic energy?

A. 50 J
B. 40 J
C. 100 J
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)

A. 490 J
B. 980 J
C. 245 J
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 5 kg object is dropped from a height of 10 m, what is its potential energy just before it hits the ground? (2021)

A. 50 J
B. 100 J
C. 150 J
D. 200 J

Solution

PE = m × g × h = 5 kg × 9.8 m/s² × 10 m = 490 J.

Correct Answer: B — 100 J

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Q. If a 5 kg object is moving with a speed of 10 m/s, what is its total mechanical energy assuming no potential energy?

A. 250 J
B. 500 J
C. 100 J
D. 50 J

Solution

Total Mechanical Energy = Kinetic Energy = 0.5 * m * v² = 0.5 * 5 kg * (10 m/s)² = 250 J.

Correct Answer: B — 500 J

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Q. If a 5 kg object is moving with a velocity of 3 m/s, what is its kinetic energy? (2023)

A. 22.5 J
B. 30 J
C. 45 J
D. 60 J

Solution

Kinetic Energy = 0.5 × mass × velocity² = 0.5 × 5 kg × (3 m/s)² = 22.5 J

Correct Answer: C — 45 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 gained by the car? (2021)

A. 200,000 J
B. 100,000 J
C. 50,000 J
D. 400,000 J

Solution

Kinetic Energy (KE) = 0.5 × mass (m) × velocity² (v²). KE = 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 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)

A. 200 J
B. 1000 J
C. 2000 J
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?

A. 200,000 J
B. 100,000 J
C. 50,000 J
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)

A. 13500 J
B. 9000 J
C. 18000 J
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 10 N is applied to move an object 3 m in the direction of the force, what is the work done?

A. 30 J
B. 10 J
C. 3 J
D. 0 J

Solution

Work done = Force * Distance = 10 N * 3 m = 30 J.

Correct Answer: A — 30 J

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Q. If a force of 15 N moves an object 3 m in the direction of the force, what is the work done? (2022)

A. 45 J
B. 30 J
C. 60 J
D. 15 J

Solution

Work done = Force × Distance = 15 N × 3 m = 45 J

Correct Answer: A — 45 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?

A. 100 J
B. 50 J
C. 20 J
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 machine does 3000 J of work in 10 seconds, what is its power output?

A. 300 W
B. 150 W
C. 600 W
D. 1000 W

Solution

Power (P) = Work (W) / Time (t) = 3000 J / 10 s = 300 W.

Correct Answer: A — 300 W

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Showing 61 to 90 of 103 (4 Pages)

Work, Energy & Power

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