Advertisements
Advertisements
प्रश्न
A bullet of mass 50 g moving with an initial velocity 100 m s-1 strikes a wooden block and comes to rest after penetrating a distance 2 cm in it. Calculate: (i) Initial momentum of the bullet, (ii) Final momentum of the bullet, (iii) Retardation caused by the wooden block and (iv) Resistive force exerted by the wooden block.
Advertisements
उत्तर
Mass, m = 50 gm = 0.05 kg.
Initial velocity, u = 100 m/s.
Final velocity, v = 0.
Distance, s = 2cm = 0.02 m.
(i) Initial momentum = mu = (0.05) (100) = 5 kg m/s-1
(ii) Final momentum = mv = (0.05) (0) = 0 kg m/s.
(iii) Acceleration, a = (v2 - u2)/2s.
Or, a = (02 - 1002)/ 2(0.02).
Or, a = -2.5 105 ms-2.
Therefore, retardation is 2.5 × 105 ms-2.
(iv) Force, F = ma
Or, F = (0.05 kg) (2.5 × 105 ms-2)
Or, F = 12500 N
APPEARS IN
संबंधित प्रश्न
Two blocks A and B of mass mA and mB , respectively, are kept in contact on a frictionless table. The experimenter pushes block A from behind, so that the blocks accelerate. If block A exerts force F on block B, what is the force exerted by the experimenter on block A?
A man has fallen into a ditch of width d and two of his friends are slowly pulling him out using a light rope and two fixed pulleys as shown in the following figure. Show that the force (assumed equal for both the friends) exerted by each friend on the road increases as the man moves up. Find the force when the man is at a depth h.
Calculate the tension in the string shown in the following figure. The pulley and the string are light and all the surfaces are frictionless. Take g = 10 m/s2.
An aeroplane is moving uniformly at a constant height under the action of two forces (i) Upward force (lift) and (ii) Downward force (weight). What is the net force on the aeroplane?
A body of mass m moving with a velocity v is acted upon by a force. Write an expression for change in momentum in each of the following cases: (i) When v << c, (ii) When v → c and (iii) When v << c but m does not remain constant. Here, c is the speed of light.
Calculate the magnitude of force which when applied on a body of mass 0.5 kg produces an acceleration of 5 m s-2.
A car is moving with a uniform velocity 30 ms-1. It is stopped in 2 s by applying a force of 1500 N through its brakes. Calculate the following values : The change in momentum of car.
What do you mean by linear momentum of a body?
Which of the following has the largest inertia?
Use Newton's second law to explain the following:
While catching a fast moving ball, we always pull our hands backwards.
