Mechanics | Relativity Answers

A 60.0 kg person running at an initial speed of 4.00 m/s jumps onto a 120 kg cart
initially at rest as shown below. The person slides on the cart’s top surface and finally comes to rest relative to the cart. The coefficient of kinetic friction between the person and the cart is μk =
0.400. Friction between the cart and the ground can be ignored.
(g) Find the displacement of the cart relative to the ground while the person is sliding on the cart.
(h) Find the change in kinetic energy of the person.
(i) Find the change in kinetic energy of the cart.

Draw a spacetime diagram in an inertial reference frame.
a) Mark any two spacelike related events on your diagram and label them
both ‘S.’
b) Mark any two lightlike related events on your diagram and label them
both ‘L.’
c) Mark any two timelike related events on your diagram and label them
both ‘T.’

A child standing on the floor of a balcony of a multi storey building, throws a ball straight upwards with an initial velocity of 10m/s. Assume the the floor is 25m high from the ground. Take g=9.8m/s/s.find the a.maximum height above the ground reached by the ball. B.velocity with which the ball strikes the ground

assuming that the planet mars has period about sun equal to 687 earth days approximately find the mean distance of mars from the sun. take the distance of the earth from the sun has 150 million km.

how the displacement of a vertically thrown ball varies with time

4. A runner maintains a constant speed of 6.0 m/s with a stride length of 1.4 m. If the runner
increases his stride length to 1.5 m without changing his stride frequency, what will his new speed
be?

f stride length is the distance between consecutive footfalls of the same foot, derive an expression
for the running speed in terms of stride length and stride frequency (cadence) the running speed
may be given by

force of 900 N was applied at angle 65o
to the running plane. Assuming a 70 % restitution,
calculate the ground reaction force that propels the athlete forward.
force of 900 N was applied at angle 65o
to the running plane. Assuming a 70 % restitution,
calculate the ground reaction force that propels the athlete forward.

1. Briefly explain the following concepts as they pertain to running.
I. At low speeds a runner increases his speed mainly by increasing length of stride.
II. At a certain (high) speed, which differs for different runners, the speed is increased mainly
by an increase of stride frequency.
III. Leg drive and not the length of legs has the greatest importance in lengthening the stride
during fast running.

A particle P has a velocity (-3i+j)m/s at a time t=0,the particle moves with constant acceleration a=(2i+3j)m/s^2.find the speed of the particle after 3secs.