Homework Help: physics

Posted by sel on Monday, March 15, 2010 at 9:21am.

(a)At a certain instant, a particle-like object is acted on by a force F = (4.0 N)i - (2.0 N)j + (9.0 N)k while the object's velocity is v = - (2.0 m/s)i + (4.0 m/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 j component. If the force is unchanged, and the instantaneous power is -12 W, what is the velocity of the object just then?

physics - bobpursley, Monday, March 15, 2010 at 10:19am
work=force dot dx
the dot product is scalar, so all the components (ii,jj,kk) are added.

b) power= d work/dt= d Force dot velocity/dt
-12watts= (4i-2j+9k) vj
vj= -12/-2 = 6j

Answer this Question

Related Questions

Physics - (a) At a certain instant, a particle-like object is acted on by a ...
Physics - At a certain instant, a particle-like object is acted on by a force F...
Physics/Math - At a certain instant, a particle-like object is acted on by a ...
physics - At a certain instant, a particle-like object is acted on by a force F...
physics - A particle is moving clockwise in a circle of radius 1.75 m. At a ...
physics - A particle is moving clockwise in a circle of radius 1.54 m. At a ...
Physics - A 5.57-kg object passes through the origin at time t = 0 such that its...
science - 1.act against the direction of motion and gets larger as an object ...
science - 1.act against the direction of motion and gets larger as an object ...
Mechanics A level? - A particle P lies on a smooth horizontal surface. It is ...

For Further Reading

First Name:
School Subject:
Answer: