Power, the rate of energy transfer

[dbigtheory]

Homework Statement

A 613.0 kg mass is placed on a forklift that can generate 950 W of power. What is the constant speed of the forklift while lifting this load?

Homework Equations

P= E/T
e=energy in joules
T= time

The Attempt at a Solution

not enough information therefore i couldn't do it. pls help

 

[zachzach]

Homework Statement

A 613.0 kg mass is placed on a forklift that can generate 950 W of power. What is the constant speed of the forklift while lifting this load?

Homework Equations

P= E/T
e=energy in joules
T= time

The Attempt at a Solution

not enough information therefore i couldn't do it. pls help

Hint: $$P = \frac{dW}{dt}$$

Where W is the work.

 

[dbigtheory]

time and work are not given, only have Watt and i have no idea wat to do with Kg and i need to find velocity...dunno

 

[zachzach]

time and work are not given, only have Watt and i have no idea wat to do with Kg and i need to find velocity...dunno

What is the equation for the work done in this problem?

 

[dbigtheory]

W= FD but i don't have the distance

 

[zachzach]

W= FD but i don't have the distance

Right, and what is F?

 

[dbigtheory]

Watt, power

 

[zachzach]

No, F is the force doing the work W = FD, what force is doing the work?

 

[dbigtheory]

i know what you're getting into but i have try that attempt before, even so I don't understand how to find the velocity with FG

 

[zachzach]

I'm trying to help you lol. If you knew what I was getting at you would already have the answer. You know what W is so what is dW/dt?

 

[dbigtheory]

velocity but i don't have the time?

 

[zachzach]

Would you please show your work. I cannot help you otherwise. Show what you have done. W is work not velocity.

 

[dbigtheory]

ok i think i get it you divide the FG by the power to find time and then divide the Fg by the time>? i think

 

[zachzach]

ok i think i get it you divide the FG by the power to find time and then divide the Fg by the time>? i think

UGH. PLEASE WRITE EQUATIONS. Let's start over, this is not that difficult you can do it I promise, but I don't want to just give you the answer. You know derivatives right?

$$P = \frac{dW}{dt}$$

Where W is the work done. So power is the rate of change of work with respect to time. So if you can write out the equation for work then all you have to do is take the derivative of it (dw/dt) and that will be equal to the power.

 

[dbigtheory]

so 950w= 6007N/dt and then i use it to find time and i know velocity?

 

[zachzach]

so 950w= 6007N/dt and then i use it to find time and i know velocity?

$$W = F_g x = mgx$$

What is dW/dt?

 

[dbigtheory]

velocity, i got 950m/s. i got the time by dividing dw by P. i think tis should be right

 

[dbigtheory]

yo man don't worry i about it. i screwed up, the answer suppose to be 0. 158m/s. thanks for your help though

 

[zachzach]

velocity, i got 950m/s. i got the time by dividing dw by P. i think tis should be right

That is 2000 mph! DO YOU KNOW DERIVATIVES?? This is what you are going to do:

FIND dw/dt (W = mgx) where x is the change in height and POST WHAT YOU GET FOR THE DERIVATIVE.

 

[zachzach]

Remember mg is a constant, but x is not.

 

[dbigtheory]

Grazie!

 

[zachzach]

No problem