CBSE Class 11-Physics: How to Solve the Force Problems: Questions (For CBSE, ICSE, IAS, NET, NRA 2022)

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How to Solve the Force Problems

1) First Draw Nice diagram of Situation and show all the forces acting the system with vector

2) Draw the Free body diagram for each body in the system and show all the forces acting on it with nice arrows and vector

3) Choose a suitable XY Coordinate system and resolve all the force on the X and Y direction. And apply equation separately to x and y components

4) Check the list of known and unknown values and solve the equations formed by Newton՚s law to reach at the value of unknown. Keep in mind, we need as many equation as many unknown values.

5) Units could be very helpful in some cases. The equation should have same unit on both sides.

Question:

Consider a three-body system shown in figure below

1) Find the acceleration of each object

2) Find the contact force between all the objects

Consider a Three Body System Shown in Figure Below

Solution

  • Let a be the acceleration of the system
  • Let be the contact force between A and B
  • Let be the contact force between B and C
  • let՚s draw free body diagram for each object
Let՚s Draw Free Body Diagram for Each Object

Solution continued

For object A

For object B

For object C

Adding and we get

Substituting the value in 1 and 3, we get

Question:

A Body of mass m moves along X axis such that at time t, its position is given by

Where are constant.

Find the acceleration of the body and force acting on it

Solution:

Velocity and acceleration could be finding out using the first and second differential

According to Newton՚s Law, Force is given by

So

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