Constant Power

Fluent

A constant direction force delivers a constant power of 45.0 W to an 8.00-kg mass which is
initially moving in the direction of the force. At t = 0 s, the force is 5.00 N.
Calculate the speed of the mass after 4.00 s.

I've tried to do several different things, however I believe you need to integrate. My intregration skills are really weak, so please don't assume I'll know what you're doing if you skip alot of steps.

Thanks.

LowlyPion

Welcome to PF.

You're in luck. You won't need to integrate.

But you will need to understand what power is.

Like what units is power expressed in?

Fluent

Kg m^2/s^3

Few more points would be helpful.

Thanks

LowlyPion

OK and how is power related to Force?

Power = Force times ...?

Fluent

velocity.. however unfortunately the answer is not 9 m/s. The other information is needed to solve this.. as the force isn't the same throughout.. (it's 5.00 N only at t = 0 s)

LowlyPion

You are jumping ahead a bit.

The 9 m/s is the speed at t=0 however.

Now think about what is a watt? A Joule/sec perhaps?

And how many seconds? So how many Joules were added to the energy of the mass? ...

And how many joules of energy did the mass have at t=0? And added together as Kinetic energy how fast does that mean the mass is going?

Fluent

Ahh thanks alot man.. appreciate it.