Question 11: When a tractor moves with uniform velocity, its heavier wheel rotates slowly than its lighter wheel. Explain. ANSWER A tractor has larger rear wheels and smaller front wheels. When a tractor moves with uniform velocity, the larger rear wheel rotates slowly than the smaller front wheels. Suppose ‘R’ is the radius of the larger wheel and ‘r’ is the radius of the smaller wheel. The linear distance covered by one rotation is given by, For larger wheel, So the linear distance covered by the larger wheel s₁ is R/r times more than the distance s₂ covered by the smaller wheel. Since ‘R’ is greater than ‘r’, their quotient is also greater than 1 and, hence, s₁ is greater than s₂. This means in the same number of rotations, the larger wheel will cover more distance than the smaller one. When the tractor is moving with uniform speed, both wheels cover same distance in same time, therefore, s₁ = s₂. In order s₁ = s₂, we should have (R/r = 1). Now for (R/r = 1), either the larger wheel rotate slowly or the smaller wheel faster. Anyways, the heavier wheel should rotate slowly than the lighter one.