Mechanics | Relativity Answers

You are trying to push a crate across the rough floor of a warehouse. Just before the crate begins to move, you have applied a force of 102 N. The shipping label on the crate says it is 61 kg. Calculate the coefficient of static friction between the crate and the floor. (Use g=9.8ms-2)

An athlete on a trampoline leaps straight up into the air with an initial speed of 6.54 m/s. Find the maximum height reached by the athlete (in meters) relative to the trampoline. Use g=9.8 ms-2 and answer to 3 SF.

A cricket bowler can bowl a 158 g ball at 147 km/hr. Calculate the kinetic energy of this bowl and use this to compare to a bowling ball that weighs 7 kg. How fast would the bowling ball need to be bowled to have the same kinetic energy as the cricket ball? (Answer to 1 d.p)

The block m1=1 kg sliding on a flat frictionless surface is connected by a string over a pulley to the hanging block m2=10kg. The system is released from the rest. Calculate the acceleration of the system

A cricket ball of mass 150 gm is moving with velocity 12 m/s and is hit by a bat so that ball is turned back with 20 m/s. The force acts for 0.01s.The average force exerted by the bat on the ball is-
a)400 N b) 450 N c) 485 N d) 480 N

Which of the following is the correct unit of k in the equation of a damped harmonic oscillator given as
−bv−kx=ma
, where b is the damping factor and all the symbols have their usual meaning?

A particle moves according to the equation x=2t^2-5t+6.Find i) average velocity in the last 3 sec ii)Velocity at t=3s.
a) 1 m/s, 7 m/s b) 4 m/s,3 m/s c)2 m/s, 5 m/s d)3 m/s, 7 m/s

A man is moving on his bike with 54km/hr. He takes a U-turn in 10s and continues to move with the same velocity. Find average acceleration during this time-
a) 3.0 m/s2 b) 1.5 m/s2 c) 0 d) -1.5 m/s2

A particle of mass m is moving in a circular path of constant radius r such that radial acceleration a=k^2+r^2.Find the power delivered to the particle by th forces acting on it.

An important news announcement is transmitted by radio waves to people who are 100km away, sitting next to their radios, and by sound waves to people sitting across the newsroom, 3.0m from the newscaster. Who receives the news first? Explain. Take the speed of sound in air to be 343 m/s.