Question

The linear momentum p of a body moving in one dimension varies with time according to the equation $p = a + bt^{2}$ where a and b are positive constants. The net force acting on the body is

• A. A constant
• B. Proportional to $t^{2}$
• C. Inversely proportional to t
• D. Proportional to t

Answer 1

Answer: (D)

Proportional to t

Answer 2

$F = \frac{dp}{dt}\bar{=}\frac{d}{dt}(a + bt^{2}) = 2bt$∴ $F \propto t$