Mechanics | Relativity Answers

A uniform 3.0 kg disk of radius 30 cm is rotating around its central axis at an angular speed of 72 rad/s. At time t = 0, a man begins to slow it at a uniform rate until it stops at t = 20 s. (a) Find its angular acceleration. (b) By time t- 10 s, how much work had the man done? (c) For full 20 s, at what average rate did the man do work?

A 5 kg object is located at a distance of 9.0 x109 km from the center of a larger object whose mass is 2.0 x 1030 kg.

a. What is the size of the force acting on the smaller object

b. What is the size of the force acting on the larger object?

c. What is the acceleration of the smaller object when it is released?

d. What is the acceleration of the larger object when it is released?

A person is holding a 5.0 kg mass in one hand as shown in the figure above.

You can ignore the mass of the forearm itself.What is the force exerted by the bicep in order to keep the arm horizontal?(in N to 2s.f)

A sound wave of frequency 300Hz travels with speed 340ms–¹along the negative x-direction. Each point of the medium moves up and down through a total distance of 5.0mm. Determine the necessary parameters to represent the wave mathematically.

A piece of metal has a mass of 200 g in air and 170 g when immersed in water. Calculate its volume and density. [Density of water is 1000 kgm-3. Take g=9.8 ms-2 ]

Joanne drives her car with a mass of 1000 kg at a speed of 20 m/s. Show that to bring her car to a halt in 10 s, road friction must exert a force of 2000 N on the car. 

the earth pulling down on a 12kg rock during the 3.0s it takes to fall a cliff?

A ball thrown vertically downward from the top of a building living the throwers hand with the velocity of 10 m per second. If the ball was through from a point 40 m above the ground how long does it take to strike the ground?

A body dropped from rest falls half its total path in the last second before it strikes ground. From what height was it dropped?