Free Work and Energy MCQs with Answers

• A. 10 J
• B. 90 J
• C. 270 J
• D. 180 J

Explanation: K.E = 1/2 mv2 K.E = v2 (m=constant) if v' = 3v ,then K.E' = 9K.E K.E'= 9K.E =9(30) K.E=270J numerical type question so only one answer…

• A. Increases
• B. Decreases
• C. Remains constant
• D. Becomes zero

Explanation: When force and displacement are in the same direction; the kinetic energy of the body increases.

• A. Truck will cover less distance before stopping
• B. Car vill cover less distance before stopping
• C. Both will cover equal distance
• D. None of the mentioned

Explanation: Being lighter than a truck, the car has less kinetic energy. On applying brakes with the same force, the car will cover less distance…

• A. 1410 ms-1
• B. 141 m s-1
• C. 1.41 ms-1
• D. 9800 ms-1

Explanation: v = √2gh v=√2x10x1000 = √20000 = 141 m/s

• A. mgh = 1/2 mv2 - fh
• B. mgh = fh - 1/2 mv2
• C. mgh = 1/2 mv2 + fh
• D. mgh = fg +1/2 mv2

Explanation: mgh = 1/2 mv2 + fh (In the presence of friction)

• A. at position 1
• B. the first time at position 3
• C. the last time at position 3

Explanation: At positions 1, 2 and finally (last time) coming to rest at 3, the speed of the ball is zero.

• A. 33 kW
• B. 3.3 kW
• C. 0.33 kW
• D. 0.033 kW

Explanation: According to the given data, weight=100kg, height=10m, time=5s, efficiency=60% work= PE = mgh = 100 x 10 x 10 = 10,000 power= work/time =…

• A. 30.6 ms-1
• B. 3.06 ms -1
• C. 0.306 m s-1
• D. 300.6 m s-1

Explanation: P = Fv P=mgv ⇨ v = P/mg = 3000/1000×10 = 0.306 ms-1

• A. 2.45 watt
• B. 245 watt
• C. 24.5 watt
• D. 2.45 k watt

Explanation: According to the given data; m= 5000g = 5 kg , g= 9.8 , h=1m , time= 2s Power= Energy/ time = P.E/time = mgh/time = (5 x 9.8 x 1) / 2 =…

• A. 5.0 kW
• B. 2.5 kW
• C. 10 kW
• D. 12.5 kW

Explanation: Since the car is moving with a constant speed, there is no chnage in KE ;hence, the power generated is due to the frictional force acting…

• A. Zero
• B. Negative
• C. Maximum
• D. Minimum

Explanation: When the applied force and the displacement are parallel to each other, the work done on the body is maximum.

• A. Work under a constant force
• B. Work under a variable force
• C. Work under a maximum force
• D. Work under a minimum force

Explanation: The curved nature of the graph shows that the force is changing and is not a straight, horizontal, constant line; hence, it represents…

• A. Remain same
• B. Double
• C. Three times
• D. Four times

Explanation: The kinetic energy (KE) of an object is given by the formula: KE = (1/2) m x v2 where m is the mass of the object and v is its velocity.

• A. 1 hp
• B. 2 hp
• C. 3 hp
• D. 4 hp

Explanation: Power = Energy/time = 9 x 10^3 / 3 = 3000 Watt Since 1 horsepower (hp) = 746 Watt 3000 Watt = 3000/746 hp = 4.021 ≈ 4 hp

• A. Zero
• B. Negative
• C. Maximum
• D. mgh

Explanation: Potential Energy = mass x acceleration due to gravity (g) x height g = 0 P.E = m x 0 x h P.E = 0 J

• A. Gravitational force
• B. Friction force
• C. Electrostatic force
• D. Magnetic force

Explanation: Only frictional force is non-conservative. The work done by this force depends upon the path taken and the energy is not conserved.

• A. Coal
• B. Uranium
• C. Oil
• D. Gas

Explanation: Uranium is the only source of energy that is not a fossil fuel. It is a naturally occuring element.

• A. 3.6 x 10^7 J
• B. 3.6 x 10^9 J
• C. 3.6 x 10^12 J
• D. 3.6 x 10^18 J

Explanation: Energy = Power x time = MWhr 1 MW = 1 x 106 W 1 hr = 3600 seconds = 36 x 102 s 1 MWhr = 1 x 106 x 36 x 102 1 MWhr = 36 x 108 J 1 MWhr =…

• A. The force of friction
• B. The force of gravity
• C. The normal force
• D. The force you pushing

Explanation: As the crate is moving at a constant speed, the net force is 0. The total of the forces exerted on the crate down the slope is equal to…

• A. Electric force
• B. Gravitational force
• C. Frictional force
• D. Magnetic force

Explanation: Only frictional force is non-conservative. The work done by this force depends upon the path taken and the energy is not conserved.