24 past paper MCQs on Work, from the Work and Energy unit of MDCAT Physics. The year each question appeared is shown where known; tap “Show answer” for the correct option and a short solution.
1.A 10 N force moves a body around a circular path of radius 50 cm. What is the work done in completing one revolution? (MDCAT 2020)
Correct answer: (b) zero
The body returns to its starting point, so the displacement is zero and so is the work.
2.The area under a force-displacement graph gives us the: (MDCAT 2020)
Correct answer: (c) work
Force multiplied by displacement is work, and that product is the area under the graph.
3.The work done by a variable force can be found by dividing the: (MDCAT 2023)
Correct answer: (b) displacement into small intervals
Over a small enough displacement the force is effectively constant, so $W=\sum F\Delta d$ is the area under the force-displacement graph.
4.Work done is equal to: (MDCAT 2024)
Correct answer: (a) effort $\times$ distance
Work is the product of the force and the distance moved in the direction of the force.
5.When a force of 1 N displaces its point of application by 1 m in the direction of the force, the work done is: (MDCAT 2024)
Correct answer: (a) 1 J
$W=Fd=1\times1=1$ J, which is how the joule is defined.
6.At what angle between the force and the displacement will the work done be maximum? (UHS MDCAT 2017)
Correct answer: (a) $0^{\circ}$
$W=Fd\cos\theta$ is largest when $\cos\theta=1$, that is when the force acts along the displacement.
7.An object of mass \$2\,\mathrm{kg}\$ is lifted vertically through a distance of \$1.5\,\mathrm{m}\$. The work done in the process is: (UHS MDCAT 2017)
Correct answer: (a) $29.4\,\mathrm{J}$
$W=mgh=2\times9.8\times1.5=29.4\,\mathrm{J}$.
8.Work done is positive if angle is: (NUMS MDCAT 2025)
Correct answer: (a) 0° < θ < 90°
$W=Fd\cos\theta$ is positive while the cosine is positive, that is for angles under $90^{\circ}$.
9.The work done by centripetal force is: (NUMS MDCAT 2025)
Correct answer: (c) Zero
The centripetal force is always at right angles to the motion, so it does no work.
10.When force and displacement are in opposite direction then the work done is said to be: (SIBA MDCAT 2025)
Correct answer: (b) Negative
With $\theta=180^{\circ}$ the cosine is $-1$, so the work is negative.
11.When a force of 1N displaces its point of application by 1m in the direction of force, the work done is (UHS MDCAT 2024)
Correct answer: (a) 1 J
$W=Fd\cos0^{\circ}=1\times1$, which is one joule.
12.How does an angle between the force applied and the direction of motion influence the work done on an object? (KMU MDCAT 2024)
Correct answer: (b) Work is maximum when the angle is 0°
$W=Fd\cos\theta$ is greatest when the cosine is one, that is when force and displacement are along each other.
13.A nurse is pushing a wheelchair with an 80kg patient sitting on it. How much work is done by the patient's weight? (KMU MDCAT 2024)
Correct answer: (d) No work
The weight acts downwards and the chair moves horizontally, so the angle is $90^{\circ}$ and the work is nil.
14.If a constant force of 10N is applied to move an object 5m in the direction of the force, what is the work done? (KMU MDCAT 2024)
Correct answer: (d) 50 J
$W=Fd=10\times5$, which is $50\,\mathrm{J}$.
15.At what angle of applied force, work done will be 50%? (NUMS MDCAT 2024)
Correct answer: (b) 60°
$\cos\theta=0.5$ gives $\theta=60^{\circ}$.
16.Work done will be negative if the angle between force and displacement is: (SZABMU MDCAT 2023)
Correct answer: (d) 180 O
At $180^{\circ}$ the cosine is $-1$, so the work is negative.
17.The area under force-displacement graph gives: (NUMS MDCAT 2023)
Correct answer: (c) Work
Force times displacement is work, and that is the area under the graph.
18.Work done by the spring force in a time interval cannot be: (PMC MDCAT 2022)
Correct answer: (c) Zero
The spring force and the displacement are along the same line, so their product is never zero while the spring moves.
19.A body is undergoing non uniform circular motion, work done by radial force on the body: (PMC MDCAT 2022)
Correct answer: (b) Zero
The radial force is always at right angles to the motion, so it does no work.
20.In a simple pendulum, work done by the tension force is? (PMC Practice 2021)
Correct answer: (c) Zero
The tension is along the string and the bob moves at right angles to it, so no work is done.
21.Two forces of 5 N and 15 N arc work on a body in opposite directions. If the body displaced by 5 m in direction of the net force, what will be the work done by a net force? (PMC Practice 2021)
Correct answer: (a) 50 J
The net force is $15-5=10\,\mathrm{N}$, and $10\times5$ is $50\,\mathrm{J}$.
22.A 1.75 m tall weight-lifter raises a weight of mass 50 kg to a height of 0.5 m above its head. How much work is being done by it? (g = 10 ms-2) (PMC MDCAT 2020)
Correct answer: (d) 1125 J
The weight is lifted from the ground to $1.75+0.5\,\mathrm{m}$, so $W=50\times10\times2.25$, that is $1125\,\mathrm{J}$.
23.Work done, due to centripetal force, for circular motion will be: (UHS MDCAT 2019)
Correct answer: (b) Zero
The centripetal force is always at right angles to the motion, so it does no work.
24.Which of the following statement shows that no work is done? (UHS MDCAT 2019)
Correct answer: (c) The moon Orbiting the earth.
The moon moves at right angles to the pull on it, so gravity does no work.