Question

A particle moves in the x – y plane under the action of a force $\overrightarrow{F}$ such that the value of its linear momentum p at any instant is p = 2(cost $\widehat{i}$ + sin t$\widehat{j}$). The angle θ between F and p is

• A. 60⁰
• B. 45⁰
• C. 30⁰
• D. 90⁰

Answer 1

Answer: (D)

90⁰

Answer 2

.(4)

Sol. F = dp/dt = 2 (-sint $\widehat{i}$ + cost$\widehat{j}$)

$\overrightarrow{F}.\overrightarrow{p}$ = 4(-sin t$\widehat{i}$ + cos t$\widehat{j}$)(cost $\widehat{i}$ + sin t$\widehat{j}$) = 0 ∴ θ = 90⁰