00:01
Hi, this question is completely based on newton's law.
00:04
We know four different laws given by newton.
00:07
He stated three laws for motion of an object and also one universal law of gravitation.
00:13
There are six different situations given in this question, for which we need to indicate which law describes the task best.
00:22
Starting with part a, first case, calculating the net force on a car as it slows down.
00:28
When a car is in motion several forces act on it like the driving force, frictional force, its weight, normal reaction.
00:38
So which of the newton's law we need to use here to explain the situation better to calculate the net force? the answer is we use newton's second law of motion.
00:52
Newton's second law, the reason because it gives the definition of force.
00:58
The law states that the rate of change of momentum of an object is directly proportional to the external unbalanced force in the direction of force that is d p by d t is proportional to f as per the law simplifying this further you will get the formula of force as f is equal to m a so using this second law we can easily calculate the net force acting on a curve next situation calculating the force exerted on a satellite by earth here obviously space we use universal law of gravitation newton's universal law of gravitation why because earth's gravity helps satellite to move in circular path earth's gravity provides the necessary centripetal force for the satellite to move in its orbit.
02:10
Next case where situation is showing the mathematical relation between mass and weight.
02:20
Here also we use newton's second law to explain it better because as per this law, f is equal to m .a.
02:37
So, w, that is weight of an object, is the force with which earth attracts it.
02:42
Hence we can write w as m into g where g is the acceleration g to gravity using this formula w is equal to m into g.
02:52
This equation relates weight and mass.
02:55
They are directly proportional.
02:58
Fourth case explaining the direction that a rubber stopper takes after the string that was keeping it moving in a circle overhead is cut.
03:09
Imagine an object moving in making circular path with the same.
03:13
Help of a string attached to the center.
03:16
If this string is cut off, what explains the direction of this object? which law could we use? here the answer would be newton's first law of motion.
03:30
It is also called law of inertia.
03:37
As per this law with no external force, when the external force is zero, when there is no external force acting on an object, the object will either remain at rest or even if it if it is moving it need to have constant speed plus it will move in same straight lane, same direction.
04:01
Its velocity will not change...