4. State Newton's second law of motion and prove F = ma
5. Newton's first law of motion is also called the law of inertia, why?
Clarify your answer.
6. An electric fan continues in its motion even after the switch is put
off, why?
Answers
4.Newton’s second law of motion states that the force exerted by a body is directly proportional to the rate of change of its momentum. For a body of mass ‘m’, whose velocity changes from u to v in time t, when force ‘F’ is applied.
F∝
Time
Changeinmomentum
F∝
t
mv−mu
F∝m(
t
v−u
)
⇒F∝ma⇒F=kma(∵a=
t
v−u
)
⇒F=ma(∵k=constant=1)
5. Newton's first law of motion states that a body at rest remains at rest, or, if in motion, remains in motion at a constant velocity unless acted on by a net external force. This is also known as the law of inertia. Inertia is the tendency of an object to remain at rest or remain in motion.
6.An electric fan is a machine which is used to create the current of air by using the blades of the fan. The electric fan contains an electric motor that converts electrical power into mechanical work.