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The angle between the normal reaction and resultant contact force is called the angle of friction(Ó¨).
Static friction is a variable force and it changes itself according to the applied force so that's why static friction is a self-adjusting force.
The term rolling friction refers to the resistance created by an object rolling across a surface. Examples of rolling friction can help you to understand this concept. You will understand this well in Rotation chapter.
The magnitude of the kinetic friction is comparatively lesser due to the low value of its coefficient than that of static friction coefficient.
Yes, sometimes friction can act in the direction of motion. For example:- A car accelerates on the road only because the frictional force on the car due to the road drives it, i.e., the car would not accelerate if tires did not push against the road and the road pushed against tires. The force that accelerates your car is the static friction against your tires in the direction you are accelerating.
Rocket Propulsion is based on the law of conservation of momentum.
Where  and  i.e Higher the mass of gun lesser will be recoil velocity
Weightlessness is the condition when apparent weight = 0. You will study this in detail in the chapter of gravitation.
When Lift is moving up with a = g then    Apparent weight = 2 (Actual weight) So the ratio of  Apparent weight to  Actual weight of the body is equal to 2.
Generally, We assume spring is massless. And Force at every point in a massless spring remains the same. If the mass of the spring is also given then Force at every point in spring will not be same.
As For three blocks, (two are hanging and one is at the rest on the smooth horizontal table) acceleration of the system So a=0  
Since Body A has greater mass than body B. So body A will move verticle downward and body B will move verticle upward with the same acceleration.
In the above figure 1) If pulled slowly string will break from point A. 2) If pulled with a sudden jerk then will experience Tension & due to inertia of rest of mass(load) F will  not be transmitted to point A,      so it will break  from B point
No As    here if we interchange the position of two masses then the acceleration of system will remain the same.
This is because that a constant component of weight force is acting opposite to the direction of motion of our vehicle. This cause our vehicle to apply more power and that is why it consumes more fuel.
When you push there is one component of force that adds to the weight of the body and hence there is more friction. When you pull the vertical component of force is against the weight of body and hence there is less overall friction. So it is easy to pull than push an object.
Because of Newton's second law of motion. Before hitting the cricketer’s hand, the ball was travelling with a speed "v" and after hitting his hand, since the speed reduces to zero in very less time, so the rate of change of momentum that is the force is very large. That is why the cricketer used to lowers his hand. By doing this,he reduces the speed of the ball slowly to zero instead of...
If two objects of different masses have the same momentum, the lighter body possesses greater velocity.
It is a physically apparent but nonexistent force felt by an observer in a noninertial frame.
If all the forces working on a body are acting on the same point then they are said to be concurrent.