(a) At a certain instant, a particle-like object is acted on by a force 2.90 N )

Question

(a) At a certain instant, a particle-like object is acted on by a force 2.90 N )i - (2.40 N)j+ (5.10N)K while the abject's velocty is (2.20m/s + (3.50m/s NJK while the obpects velodty is v=-(2.20m/s)/+1350m/s)k What is the instantaneous rate at which the force does work on the object? (b) At some other time, the velocity consists of only a y component. If the force is unchanged, and the instantaneouts power is -7.70 W, what is the velocity of the object just then? (Give your answer without a unit vector) (a) Number (b) Number Units Units By accessing this Question Assistance, you will learn while you earn points based on the Point Potential Policy set by your instructor tern "no. ana Question Attempts: Oo, 2 used Earn Maximum Points available enly if you answer this question conrecty in your ferst

Explanation / Answer

Force F = 2.9 i - 2.4 j + 5.1 k   N

velcoity   v = 2.2 i + 3.5 K   m/s

Workd done W = F.s

rate of work done = dW/dt   = F .ds/dt   ; F is const. over time but s is varying as the object has dispalcement.

                                              = F. v   = (2.9 i - 2.4 j + 5.1 k ) . (2.2 i + 3.5 K )

                                                            = 24.23 J/s

b) velocity contians only y component

                      v = m j

instantaneous Power    = -7 w

displacement is only in y-direction ; wokr is done only by the y-component of the Force i.e - 2.4 N

velcoity = -7 /-2.4 = 2.92 m/s

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