## A car weighs 1800 kg.

[question] Question. A car weighs 1800 kg. The distance between its front and back axles is 1.8 m. Its centre of gravity is 1.05 m behind the front axle. Determine the force exerted by the level ground on each front wheel and each back wheel. [/question] [solution] solution: Mass of the car, m = 1800 kg Distance between the front and back axles, d = 1.8 m Distance between the C.G. (centre of gravity) and the back axle = 1.05 m The various forces acting on the car are shown in the following figur...

## A child sits stationary at one end of a long trolley moving uniformly

[question] Question. A child sits stationary at one end of a long trolley moving uniformly with a speed V on a smooth horizontal floor. If the child gets up and runs about on the trolley in any manner, what is the speed of the CM of the (trolley + child) system? [/question] [solution] solution: No change The child is running arbitrarily on a trolley moving with velocity v. However, the running of the child will produce no effect on the velocity of the centre of mass of the trolley. This is becau...

## Give the location of the centre of mass of a

[question] Question. Give the location of the centre of mass of a (i) sphere, (ii) cylinder, (iii) ring, (iv) cube, each of uniform mass density. Does the centre of mass of a body necessarily lie inside the body? [/question] [solution] solution: Geometric centre; No The centre of mass (C.M.) is a point where the mass of a body is supposed to be concentrated. For the given geometric shapes having a uniform mass density, the C.M. lies at their respective geometric centres. The centre of mass of a ...