Mechanics | Relativity Answers

. A boy on a 20 m high cliff drops a stone. One second later, he throws down another stone such that
both the stones hit the ground simultaneously. Find the initial velocity of the second stone. (g = 10 ms-2
)

a force 80N extends a natural length 8m by 0.4m,what will be the length of the spring when the applied force is 100N

initial velocity of a train is 35m/s and acceleration produced is 2m/s(square) in 6seconds. what is its final velocity?

In 1954 the English runner Roger Bannister broke the four-minute barrier for the mile with a time of 3:59.4 s (3 min and 59.4s). In 1999 the Moroccan runner Hicham el-Guerrouj set a record of 3:43.13 s for the mile. If these two runners had run in the same race, each running the entire race at the average speed that earned him a place in the record books, el-Guerrouj would have won by how many meters?

A car travels from stop A to stop B with a speed of 30 km/hr and then returns back to A with a speed of 50 km/hr. Find : (i)displacement, (ii)distance, (iii) average velocity, (iv)average speed of the car.

A ball thrown down from the top of a tower takes time t1 to reach the ground. It takes time t2 to reach
the ground if it is thrown from the same point with the same speed in the upward direction. Show that the
time it will take to fall freely to the ground from the top of the tower is
(t1t2)^1/2
. (Neglect air resistance)

What is inertial frame?

A bullet of mass 50 g moving with an initial velocity of 100 m/s, strikes a wooden block and comes to rest after penetrating a distance of 2 cm in it. Calculate the retardation caused by the wooden block.

a train starts its journey with constanttacceleration alpha ,attains a velocity v and then moves with v for some distance and then deaccelerates at the rate of beta to come to rest .if the total length of the path covered is L, find out the total time interval of motion

The position vector of a particle is r= (t^2 - 1) i + 2t j. How can I find out the trajectory of the particle in the XY-plane ?