# Net power H E L P ! ! !

1. Oct 6, 2004

### songokou77

A car (m = 760 kg accelerates uniformly from rest up an inclined road which rises uniformly, to a height, h = 44 m. Find the net power the engine must deliver to reach a speed of 20.7 m/s at the top of the hill in 22.5s (NEGLECT frictional losses: air and rolling, ...)

I know that W_n=Triangle_K (change in K) which is 1/2*m*(V_f^2-V_i^2) where V_i = 0
and I also have that W_g+W_f=1/2 m

I tried solving with that , but I dont get it right

What am I doing wrong?; Also what do I use Velocity and Time for?( I know what for , but where in the equations do I use it if it is to be used).

2. Oct 6, 2004

### NateTG

You're missing some of the terms in your work-energy equation since the car is going uphill.

The equation should be:
$$\Delta E = W_{net}$$

3. Oct 6, 2004

### songokou77

I still dont get it after that...

4. Oct 6, 2004

### NateTG

Can you set up the energy equation? You should get about $$4.9 \times 10^5$$ joules.