Forces and Laws...

When two identical balls are moving with equal speeds in opposite directions, which of the following is true for the system of two bodies?

A ball of mass $$0.2 \ kg$$ is thrown vertically upwards by applying a force by hand. If the hand moves $$0.2 \ m$$ while applying the force and the ball goes upto $$2 \ m$$ height further, find the magnitude of force applied by the hand. Consider $$g =10$$ $${ ms }^{ -2 }$$.

When you are holding a ball in your hand, the reaction force to the force of gravity on the ball is, the force exerted by the:

If a net force $$F$$ applied to an object of mass $$m$$ will produce an acceleration of $$a$$, what is the mass of a second object which accelerates at $$5a$$ when acted upon by a net force of $$2F$$?

A block weighing $$30 \ N$$ is on a smooth horizontal surface and it is accelerated in the horizontal direction at a rate of $${4 \ m/s}^{ 2 }$$ by a force. The net force in horizontal direction acting on the block is (g $$={ 10  m/s }^{ 2 }$$ ):

A body of mass $$2 \ kg$$ moving on a horizontal surface with an initial velocity of $$4 \ ms^{-1}$$, comes to rest after $$2 \ s$$. If one wants to keep this body moving on the same surface with a velocity of $$4ms^{-1}$$, the force required is:

Inside a railway car a plumb bob (a heavy mass suspended by a thread) is suspended from the roof and a helium filled balloon is tied by a string to the floor of the car. When the railway car accelerates to the right, then

A father and his seven year old son are facing each other on ice skates (assume no friction with the ground). With their hands, they push off against one another. Regarding the forces that act on them as a result of this and the accelerations they experience. Which of the following statements is correct?

A person weighing 60 kg in a small boat of mass 140 kg that is at rest, throws a 5 kg stone in the horizontal direction with a velocity of $$14ms^{-1}$$ . The magnitude of velocity of the boat immediately after the throw is:

A bullet of mass $$10\ g$$ moving with a horizontal velocity $$100\   m/s$$ passes through a wooden block of mass $$100\ g$$. The block is resting on a smooth horizontal floor. After passing through the block the velocity of the bullet is $$10\ m/s$$. The velocity of the emerging bullet with respect to the block is: