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Common Forces In Mechanics MCQ - Practice Questions with Answers

Edited By admin | Updated on Sep 25, 2023 25:23 PM | #NEET

Quick Facts

  • Common forces in mechanics is considered one of the most asked concept.

  • 7 Questions around this concept.

Solve by difficulty

Two objects resting on a table. Mass of object 1 (m1) = 1 kg, mass of object 2 (m2) = 2 kg, Acceleration due to gravity (g) =9.8 m/s2. Determine the magnitude and direction of the normal force (R1) exerted by m2 on the m1 and the normal force (R2) exerted by the table on the m2.

A body of mass 1 kg lies on a smooth inclined plane. A force F=10m is applied horizontally on the block as shown. The magnitude of normal reaction by the inclined plane on the block is

A spring whose unstretched length is I has a force constant k. The spring is cut into two pieces of unstretched lengths l1 and l2 where l1=nl2 and n is an integer. The ratio k1/k2 of the corresponding force constants, k1 and k2 will be:

 

An Atwood machine has masses 5Kg and 15 Kg as shown. What is the acceleration (in m/s2) at 15 Kg  mass when the system is released from rest 

 

A massless rope is fixed at one end as shown in Fig. Two boys of masses 40 kg and 60 kg are moving along the rope. The former climbs up with an acceleration of 2 m/s2 while later coming down with a constant velocity of 5 m/s. The tension (in N ) at fixed support will be ( g=10 m/s2 )

An object resting on a table, is shown in the figure below. The mass of the object is 1 kg. Acceleration due to gravity is 9.8 ms2. Determine the normal force (in N ) exerted on the object by the table.

Concepts Covered - 1

Common forces in mechanics
  1. Gravitational force (Weight):-

  • Definition- Force with which earth attracts an object.

  • It always acts towards the center of the earth

  • It is denoted by W=mg, where m=mass of the body and g= acceleration due to gravity.

                                                      

2.    Normal Reaction(N or R):-

  • Definition- A force which is perpendicular to the surface in contact or point of contact of two

Surfaces.

                  

3.    Tension(T):-

  • Force exerted by taut string, rope or chain against pulling force.

  • Its unit is also Newton.

  • It acts away from the point of contact.

  • Tension remains the same as long as the string is the same only in case of a massless string.

4.    Spring Force:-

  • Spring force is also called restoring force.

  • F=Kx 

           where k is the spring constant and its unit is N/m and x is net elongation or compression in the spring.

  • Here -ve sign is because the force exerted by the spring is always in the opposite direction to the displacement. 

5.    Friction:-

  • Friction is the force that acts in the direction opposite to relative motion.

  • It acts between two surfaces in contact.

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Common forces in mechanics

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