14 past paper MCQs on Newton’s Laws of Motion, from the Force and Motion 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 fireman slides down a rope whose breaking load is three quarters of his weight. With what acceleration should the fireman slide down, if the acceleration due to gravity is $g$? (MDCAT 2022)
Correct answer: (b) $g/4$
The rope can pull up with at most $\tfrac{3}{4}mg$, so $ma=mg-\tfrac{3}{4}mg$ and $a=g/4$.
2.According to Newton's laws of motion the mass of an object is a quantitative measure of its: (MDCAT 2024)
Correct answer: (b) inertia
The greater the mass, the greater the force needed for a given acceleration, so mass measures inertia.
3.A passenger standing in a stationary bus. When the bus suddenly starts moving forward, the passenger falls backward. Which phenomenon best explains this observation? (KMU MDCAT 2025)
Correct answer: (c) Inertia
The passenger keeps the state of rest while the floor moves forward under them.
4.According to Newton's Law of Motion the mass of the object is a quantitative measure of its: (UHS MDCAT 2024)
Correct answer: (b) Inertia
Mass measures how strongly a body resists a change in its motion, that is its inertia.
5.____ is the natural tendency of an object to remain at rest or in motion with constant velocity? (KMU MDCAT 2024)
Correct answer: (b) Inertia
Inertia is the tendency of a body to keep its state of rest or of uniform motion.
6.A fireman wants to slide down a rope. The breaking load of the rope is 3/4 th of the weight of the man. With what acceleration should the fire man slide down? ( Acceleration due to gravity is 'g') (UHS MDCAT 2023)
Correct answer: (b) g/4
The rope will bear only $3mg/4$, so the least downward force is $mg/4$ and the acceleration $g/4$.
7.Is it possible to have a non-zero number of forces acting on an object (of non-zero mass), yet the object doesn’t accelerate? (PMC MDCAT 2022)
Correct answer: (b) Yes
If the forces balance, the resultant is zero and the body does not accelerate.
8.Which of the following is true about newton’s laws of motion? (PMC MDCAT 2022)
Correct answer: (c) All of them are related to forces
The first defines force, the second measures it and the third pairs it with its reaction.
9.The value of acceleration due to gravity: (PMC MDCAT 2022)
Correct answer: (c) Is least on equator
The Earth bulges at the equator, so the surface there is furthest from the centre and $g$ is least.
10.An eagle of mass 4 kg is locked inside a cage of mass 2 kg. If the eagle starts flying, what will be the mass of the bird and cage assembly? (PMC MDCAT 2022)
Correct answer: (d) 6 kg
The cage is closed, so the eagle and the cage remain one system of $6\,\mathrm{kg}$ whether it flies or not.
11.A man of mass 50 kg on the top floor of a skyscraper steps into an elevator. (PMC MDCAT 2022)
Correct answer: (c) 425 N
With the lift accelerating down, the floor pushes up with $m(g-a)=50\times8.5$, that is $425\,\mathrm{N}$.
12.If we are standing in a bus and the driver applies a brake then we feel: (PMC Practice 2021)
Correct answer: (b) A pseudo force pushes forwards
The bus slows but we keep our forward motion, which feels like a push forward.
13.Newton first law of motion is also known as: (UHS MDCAT 2018)
Correct answer: (a) Law of inertia
The first law says a body keeps its state unless a force acts, which is the law of inertia.
14.A man in elevator ascending with an acceleration will conclude that his weight is: (UHS MDCAT 2016)
Correct answer: (a) Increased
The floor must push up with $m(g+a)$, and that is what the man feels as his weight.