# Basic physics questions work and energy

1. Feb 6, 2012

### invincible1

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

the man having the weight of 75kg is able to run up a 4.5 m high flight of stairs in 4s. determine the power generated. how long would a 100w light bulb have to burn to expend the same amount of energy?

2. Relevant equations

3. The attempt at a solution
I havnt done these types of questions for a while so ive forgotten, so far ive calculated the work done by weight -75*9.81 (4.50) = -3310.8
can anyone help me solve the rest pleasE?
thanks

2. Feb 6, 2012

### Staff: Mentor

Power = rate of doing work

3. Feb 6, 2012

### invincible1

yea but i dont know how to do it

4. Feb 6, 2012

### Staff: Mentor

How much work is done in 4 seconds?

5. Feb 6, 2012

### invincible1

power=f.v but i dont know how to get the v and f?

6. Feb 6, 2012

### Staff: Mentor

As you know how much work was done in 4 secs, then divide by 4 secs and you have power!

Also, don't forget work = energy

7. Feb 6, 2012

Ok thanks