Friction always acts in a direction _______ to the direction of motion.

A shell is fired from cannon with a velocity $v\;{\rm{m}}{{\rm{s}}^{ - 1}}$ at an angle of $heta$ with the horizontal direction. At the highest point in its path, it explodes into 2 pieces of equal masses. One of the pieces retraces its path to the cannon. The speed of the other piece immediately after the explosion is

A 10 kg block is being pushed on a rough horizontal surface with a force of 50 N. The coefficient of kinetic friction between the block and the surface is 0.3. What is the acceleration of the block?

A body of mass 1000 kg is moving horizontally with a velocity 50 m/s. A mass of 250 kg is added. Find the final velocity

A block of mass 2 kg is placed on a rough horizontal surface with coefficient of static friction 0.5 and kinetic friction 0.4. If a horizontal force of 8 N is applied to the block, what will be the acceleration of the block?

A ball of mass 0.5 kg moving with a velocity of 2 m/sec strikes a wall normally and bounces back with the same speed. If the time of contact between the ball and the wall is one millisecond, the average force exerted by the wall on the ball is

In which of the following cases forces may not be required to keep the

A bullet of mass 10 g moving with 300 m/s hits a block of ice of mass 5 kg and drops dead. The velocity of ice is

A shell is fired with a muzzle velocity of $20\,m{s^{ - 1}}$ at an angle of ${60^0}$ with the horizontal. At the top of trajectory the shell explodes into 2 fragments of equal masses. One of them comes to rest. The distance at which second fragment touches the ground from gun will be…. $\left( {g = 10\,m/{s^2}} \right)$

A block of mass 2 kg is placed on a horizontal surface with coefficient of static friction μs = 0.5 and kinetic friction μk = 0.4. A force F is applied at an angle θ = 30° with the horizontal. What is the minimum force F required to just start moving the block?

A block of mass 2 kg is placed on a rough horizontal surface with coefficient of static friction μs = 0.5. What is the minimum horizontal force needed to just start moving the block?