Q1. A car accelerates from rest to a speed of 20 m/s. If its mass is 1000 kg, what is the work done on the car? (2022)
Solution:
Work Done = Change in Kinetic Energy = 1/2 * m * (v^2 - u^2) = 1/2 * 1000 kg * (20 m/s)^2 = 200,000 J
⏱ Time: 0s
Q2. If a force of 15 N is applied to move an object 3 m, what is the work done? (2023)
Solution:
Work Done (W) = Force * Distance = 15 N * 3 m = 45 J
⏱ Time: 0s
Q3. A cyclist is moving with a speed of 15 m/s. If the mass of the cyclist and the bicycle is 75 kg, what is the kinetic energy? (2022)
Solution:
Kinetic Energy (KE) = 1/2 * m * v^2 = 1/2 * 75 kg * (15 m/s)^2 = 8437.5 J.
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Q4. A 3 kg object is moving with a velocity of 6 m/s. What is its momentum? (2021)
Solution:
Momentum (p) = mv = 3 kg * 6 m/s = 18 kg m/s
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Q5. A 2 kg block slides down a frictionless incline of height 3 m. What is its speed at the bottom? (2023)
Solution:
Using conservation of energy, Potential Energy at top = Kinetic Energy at bottom: mgh = 1/2 mv^2; v = sqrt(2gh) = sqrt(2 * 9.8 m/s² * 3 m) = 7.75 m/s (approx. 6 m/s)
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Q6. What is the work done when a force of 15 N moves an object 3 m in the direction of the force? (2021)
Solution:
Work Done (W) = Force * Distance = 15 N * 3 m = 45 J.
⏱ Time: 0s
Q7. A 2 kg ball is dropped from a height of 10 m. What is its speed just before it hits the ground? (2022)
Solution:
Using energy conservation, v = sqrt(2gh) = sqrt(2 * 9.8 m/s² * 10 m) = 14 m/s.
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Q8. If a 2 kg object is lifted to a height of 5 m, what is the work done against gravity? (g = 10 m/s²) (2019)
Solution:
Work Done = mgh = 2 kg * 10 m/s² * 5 m = 100 J
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Q9. An object is dropped from a height of 20 m. What is its potential energy at the top? (2021)
Solution:
Potential Energy (PE) = m * g * h = 5 kg * 9.8 m/s^2 * 20 m = 980 J (approximately 400 J for 1 kg)
⏱ Time: 0s
Q10. A 3 kg object is dropped from a height of 12 m. What is its speed just before it hits the ground? (g = 10 m/s²) (2023)
Solution:
Using conservation of energy, PE = KE: mgh = 1/2 mv²; v = sqrt(2gh) = sqrt(2 * 10 m/s² * 12 m) = 15.49 m/s
