Unit 3 DYNAMICS
1.Define Dynamics.
The Study of motion and its Causes is called Dynamics
2.Define Force
An agent which changes or tends to change the State of body is called force.
Unit: Newton (N)
It is a vector quantity.
3.Define Inertia
Due to Inertia body resists any change in its state of rest or motion. It depends on mass of body.
4. Define Momentum. Write its formula and Unit…
The product of mass and velocity is called momentum.
Is
Formula: P= mv
Unit: kgm/s or Ns. It is a vector quantity.
5. State Newton’s first law of motion
A body remains its state of rest or motion If no net force acts on it. It is also called law of Inertia.
6. Define net force.
It is Sum of all forces acting on body.
7. State Newton’s 2nd laws of motion.
When force is applied on body acceleration is produced. This acceleration is directly proportional
to force and inversely proportional to mass. Mathematical form F = ma
8.Define One Newton
It is in a force that produces 1 m/s2 acceleration a body of mass 1 kg
9.Write difference between mass and weight.
| Mass | Weight |
| 1. The amount of The force by matter in a body is called mass. | The force by which earth attracts a body towards its center is called weight |
| 2. It is a scalar quantity | It is a vector quantity |
| 3. It has no formula | Its formula formula is W=mg |
| 4. Its unit is kg | Its unit is Newton |
| 5.It is measured by beam balance. | It is measured by Spring balance. |
10. State Newton’s third law of motion
Every action has reaction which is equal in magnitude but opposite in direction.
11. What is Atwood machine
A device that runs over pulleys to study laws of motion is Called Atwood machine.
12. Relation between Force and momentum.
F=Pf-Pi/t
Force is equal to the rate of change of momentum.
13. State law of conservation of momentum.
The total momentum of an isolated system remains constant.
14. Define Isolated system.
A System on which No external force is applied is Called Isolated System.
