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Answer:
Q1 .A reaction force is exerted on the horse in the forward direction. ... An equal force in the opposite direction (forward direction) is applied on the horse by the Earth. This force moves the horse and the cart forward. As a result, the cart moves forward.
Q2. When a fireman holds a hose, which is ejecting large amounts of water at a high velocity, then a reaction force is exerted on him by the ejecting water in the backward direction. Hence, it is difficult for him to remain stable while holding the hose.
Q3. By Newton's second law
Force is propotional to rate of change of momentum and we finally have
F = dp/dt =d (mv)/dt = dm/dt*v+ m*dv/dt (But as per Einstein’s equation mass can be assumed to be constant at velocities <<< speed of light ) so this equation can be simplified to
=m*dv/dt = ma
Hence force required is equal to mass*acceleration = 50kg * 2ms^-2
Q4. An object of 50 kg gets the speed of 10m/s in 5 second from zero veloc ity. Calculate the required force applied by engine of the car. Initial velocity (u) = 0, final velocity (v) = 10m/s, time (t) = 5 second, Mass (m) = 50 kg, Therefore, force (F)=?
Q5. As per the question, the mass weight of the bullet is 5gm.5gm = 5/1000 kg = 0.005 kg/The pistol weighs 1.5 kg.
The velocity of the pistol is 1.5 m /second
We have to find out the velocity of the bullet..Suppose, it is V.
So, the velocity of the bullet (V) = mass of pistolx velocity of pistol / mass of bullet.or, V= 1.5 x 1.5 / 0.005.or, V = 2.25 / 0.005.or, V = 450 m / second.
The velocity of the bullet is 450 m/sec.