Question

On a given planet, the weight of an object varies directly with the mass of the object. Suppose that an object whose mass is 7 kg weighs 49 N. Find the weight

of an object whose mass is 3 kg.

Answer 1

21 N

Explanation:

let mass be m and weight be w

Given w varies directly with m then the equation relating them is

w = km ← k is the constant of variation

To find k use the condition m = 7 , w = 49 , then

49 = 7k ( divide both sides by 7 )

7 = k

w = 7m ← equation of variation

When m = 3 , then

w = 7 × 3 = 21 N