# WORK-KE help?

1. Apr 5, 2010

### lolcatz

1. The problem statement, all variables and given/known data

The 2008 dodge viper srt uses a v-10 engine to develop more than 600HP of the power,

question- If the mass of the viper is 1560 kg, what work must be done by the car to accelerate from rest to 30m/s>

2. Relevant equations

I am confused on what formula to use

3. The attempt at a solution

I did.. KE=1/2mv^2.... so...1/2(1560KG)(30m/s)^2... is this correct?

2. Apr 5, 2010

### Cilabitaon

Yes.

Out of interest, what other formulae do you have at your disposal?]

this is the energy transfer, not power.

For power there are several equations available:

$$W = F \cdot \Delta d$$

$$P(t) = F(t) \cdot v(t)$$

$$P = \frac{W}{\Delta s}$$

and also remember that horsepower can be converted to SI units of power.

Last edited: Apr 5, 2010
3. Apr 5, 2010

### lolcatz

its a take home quiz... the formulas stated are... KE, PE, work, power and %lost

i was hesitant because Joules obtained from the KE formula are not units of work? am i correct?

4. Apr 5, 2010

### Cilabitaon

That is correct, the units of work are Watts; $$W$$, or in other terms:

$$Js^{-1}$$;

$$kg \cdot m^{2} s^{-3}$$;

$$N \cdot ms^{-1}$$

As you can see, all of these units involve a measurement of time, so are you sure there is not mention of time in the question?

edit: you are confusing me haha; the units of work ARE joules, so the work done is the $$E_{k}$$

Last edited: Apr 5, 2010
5. Apr 5, 2010

### lolcatz

well ...

part B of the question says... if the car does this work in a time of 4 seconds, what power did the car develop?
could you use this on part A?

6. Apr 5, 2010