Q. A 1 kg ball is thrown upwards with a speed of 20 m/s. What is the maximum height it reaches? (g = 10 m/s²) (2021)
A.
20 m
B.
40 m
C.
30 m
D.
10 m
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Solution
Maximum Height (h) = v^2 / (2g) = (20 m/s)^2 / (2 * 10 m/s²) = 20 m
Correct Answer: A — 20 m
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Q. A 10 kg block slides down a frictionless incline of height 5 m. What is its speed at the bottom? (2020)
A.
5 m/s
B.
10 m/s
C.
15 m/s
D.
20 m/s
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Solution
Using conservation of energy, PE at top = KE at bottom. mgh = 1/2 mv^2. 10 kg * 9.8 m/s^2 * 5 m = 1/2 * 10 kg * v^2. Solving gives v = 10 m/s.
Correct Answer: B — 10 m/s
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Q. A 10 kg block slides down a frictionless incline of height 5 m. What is its speed at the bottom? (g = 10 m/s²) (2020)
A.
10 m/s
B.
5 m/s
C.
15 m/s
D.
20 m/s
Show solution
Solution
Using conservation of energy, PE at top = KE at bottom: mgh = 1/2 mv²; v = sqrt(2gh) = sqrt(2 * 10 m/s² * 5 m) = 10 m/s
Correct Answer: A — 10 m/s
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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 = 10 m/s²) (2022)
A.
200 J
B.
100 J
C.
50 J
D.
300 J
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Solution
Potential Energy (PE) = m * g * h = 10 kg * 10 m/s² * 20 m = 2000 J
Correct Answer: A — 200 J
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Q. A 10 kg object is dropped from a height of 20 m. What is its speed just before it hits the ground? (g = 10 m/s²) (2022)
A.
20 m/s
B.
10 m/s
C.
15 m/s
D.
5 m/s
Show solution
Solution
Using the formula v = √(2gh) = √(2 * 10 m/s² * 20 m) = √400 = 20 m/s.
Correct Answer: A — 20 m/s
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Q. A 10 kg object is dropped from a height of 5 m. What is its potential energy at the top? (2021)
A.
50 J
B.
100 J
C.
200 J
D.
25 J
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Solution
Potential Energy (PE) = m * g * h = 10 kg * 9.8 m/s^2 * 5 m = 490 J.
Correct Answer: B — 100 J
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Q. A 10 kg object is moving with a velocity of 4 m/s. What is its total mechanical energy if it is at a height of 5 m? (2020)
A.
120 J
B.
140 J
C.
100 J
D.
80 J
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Solution
Total Mechanical Energy = Kinetic Energy + Potential Energy = (1/2 * 10 kg * (4 m/s)²) + (10 kg * 9.8 m/s² * 5 m) = 80 J + 490 J = 570 J
Correct Answer: B — 140 J
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Q. A 2 kg ball is dropped from a height of 10 m. What is its speed just before it hits the ground? (g = 10 m/s²) (2023)
A.
10 m/s
B.
14 m/s
C.
20 m/s
D.
15 m/s
Show solution
Solution
Using conservation of energy, Potential Energy at height = Kinetic Energy just before hitting ground. mgh = 1/2 mv^2. Solving gives v = sqrt(2gh) = sqrt(2 * 10 m/s² * 10 m) = 14.14 m/s.
Correct Answer: A — 10 m/s
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Q. A 2 kg ball is dropped from a height of 20 m. What is its speed just before it hits the ground? (g = 10 m/s²) (2023)
A.
10 m/s
B.
20 m/s
C.
15 m/s
D.
5 m/s
Show solution
Solution
Using energy conservation, Potential Energy = Kinetic Energy at the ground: mgh = 0.5 mv^2; v = sqrt(2gh) = sqrt(2 * 10 m/s² * 20 m) = 20 m/s
Correct Answer: B — 20 m/s
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Q. A 2 kg block slides down a frictionless incline of height 3 m. What is its speed at the bottom? (2023)
A.
6 m/s
B.
3 m/s
C.
4 m/s
D.
5 m/s
Show solution
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)
Correct Answer: A — 6 m/s
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Q. A 2 kg object is dropped from a height of 20 m. What is its speed just before it hits the ground? (g = 10 m/s²) (2023)
A.
20 m/s
B.
10 m/s
C.
15 m/s
D.
5 m/s
Show solution
Solution
Using the formula v = √(2gh) = √(2 * 10 m/s² * 20 m) = √400 = 20 m/s
Correct Answer: A — 20 m/s
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Q. A 2 kg object is lifted to a height of 3 m. What is the work done against gravity? (g = 9.8 m/s²) (2023)
A.
58.8 J
B.
19.6 J
C.
29.4 J
D.
39.2 J
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Solution
Work Done = mgh = 2 kg * 9.8 m/s² * 3 m = 58.8 J
Correct Answer: A — 58.8 J
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Q. A 2 kg object is moving with a velocity of 4 m/s. What is its kinetic energy? (2023)
A.
16 J
B.
8 J
C.
4 J
D.
32 J
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Solution
Kinetic Energy (KE) = 1/2 * m * v^2 = 1/2 * 2 kg * (4 m/s)^2 = 16 J.
Correct Answer: A — 16 J
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Q. A 2 kg object is moving with a velocity of 4 m/s. What is its momentum? (2020)
A.
8 kg m/s
B.
4 kg m/s
C.
2 kg m/s
D.
16 kg m/s
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Solution
Momentum (p) = m * v = 2 kg * 4 m/s = 8 kg m/s
Correct Answer: A — 8 kg m/s
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Q. 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)
A.
15 m/s
B.
10 m/s
C.
12 m/s
D.
20 m/s
Show solution
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
Correct Answer: A — 15 m/s
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Q. A 3 kg object is lifted to a height of 4 m. What is the gravitational potential energy gained? (2023)
A.
120 J
B.
60 J
C.
30 J
D.
90 J
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Solution
Potential Energy (PE) = m * g * h = 3 kg * 9.8 m/s^2 * 4 m = 117.6 J (approximately 120 J)
Correct Answer: A — 120 J
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Q. A 3 kg object is moving with a velocity of 2 m/s. What is its kinetic energy? (2021)
A.
6 J
B.
12 J
C.
3 J
D.
9 J
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Solution
Kinetic Energy (KE) = 1/2 * m * v^2 = 1/2 * 3 kg * (2 m/s)^2 = 6 J
Correct Answer: B — 12 J
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Q. A 3 kg object is moving with a velocity of 6 m/s. What is its momentum? (2021)
A.
18 kg m/s
B.
12 kg m/s
C.
9 kg m/s
D.
6 kg m/s
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Solution
Momentum (p) = mv = 3 kg * 6 m/s = 18 kg m/s
Correct Answer: A — 18 kg m/s
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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 work done on the car? (2022)
A.
200,000 J
B.
100,000 J
C.
50,000 J
D.
400,000 J
Show solution
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
Correct Answer: A — 200,000 J
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Q. A cyclist is moving at a speed of 10 m/s. If he doubles his speed, how much more kinetic energy will he have? (2023)
A.
4 times
B.
2 times
C.
3 times
D.
1.5 times
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Solution
Kinetic Energy is proportional to the square of the speed. If speed is doubled, KE increases by a factor of 2^2 = 4.
Correct Answer: A — 4 times
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Q. A cyclist is moving with a speed of 10 m/s. If he doubles his speed, how much more kinetic energy will he have? (2023)
A.
4 times
B.
2 times
C.
3 times
D.
1.5 times
Show solution
Solution
Kinetic Energy is proportional to the square of the speed. If speed is doubled, KE increases by a factor of 2^2 = 4.
Correct Answer: A — 4 times
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Q. 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)
A.
8437.5 J
B.
1687.5 J
C.
5625 J
D.
2250 J
Show solution
Solution
Kinetic Energy (KE) = 1/2 * m * v^2 = 1/2 * 75 kg * (15 m/s)^2 = 8437.5 J.
Correct Answer: A — 8437.5 J
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Q. A spring is compressed by 0.1 m and has a spring constant of 200 N/m. What is the potential energy stored in the spring? (2019)
A.
1 J
B.
2 J
C.
0.5 J
D.
4 J
Show solution
Solution
Potential Energy (PE) = 1/2 * k * x^2 = 1/2 * 200 N/m * (0.1 m)^2 = 1 J
Correct Answer: A — 1 J
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Q. A spring is compressed by 0.2 m and has a spring constant of 500 N/m. What is the potential energy stored in the spring? (2023)
A.
10 J
B.
5 J
C.
20 J
D.
2 J
Show solution
Solution
Potential Energy in Spring (PE) = 1/2 kx^2 = 1/2 * 500 N/m * (0.2 m)^2 = 10 J
Correct Answer: A — 10 J
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Q. An object is dropped from a height of 20 m. What is its potential energy at the top? (2021)
A.
200 J
B.
400 J
C.
600 J
D.
800 J
Show solution
Solution
Potential Energy (PE) = m * g * h = 5 kg * 9.8 m/s^2 * 20 m = 980 J (approximately 400 J for 1 kg)
Correct Answer: B — 400 J
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Q. If a 1000 kg car is moving at a speed of 36 km/h, what is its kinetic energy? (2021)
A.
500 J
B.
1000 J
C.
2000 J
D.
3000 J
Show solution
Solution
Convert speed to m/s: 36 km/h = 10 m/s. KE = 1/2 * m * v^2 = 1/2 * 1000 kg * (10 m/s)^2 = 50000 J.
Correct Answer: C — 2000 J
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Q. If a force of 10 N moves an object 5 m in the direction of the force, what is the work done? (2020)
A.
50 J
B.
10 J
C.
5 J
D.
25 J
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Solution
Work Done (W) = Force (F) * Distance (d) = 10 N * 5 m = 50 J
Correct Answer: A — 50 J
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Q. If a machine does 200 J of work in 10 seconds, what is its power? (2022)
A.
20 W
B.
10 W
C.
30 W
D.
40 W
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Solution
Power (P) = Work / Time = 200 J / 10 s = 20 W
Correct Answer: A — 20 W
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Q. If a machine does 200 J of work in 5 seconds, what is its power? (2022)
A.
40 W
B.
50 W
C.
20 W
D.
30 W
Show solution
Solution
Power (P) = Work Done (W) / Time (t) = 200 J / 5 s = 40 W
Correct Answer: B — 50 W
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Q. If a machine does 2000 J of work in 5 seconds, what is its power? (2022)
A.
400 W
B.
200 W
C.
100 W
D.
500 W
Show solution
Solution
Power (P) = Work Done / Time = 2000 J / 5 s = 400 W
Correct Answer: A — 400 W
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