# Physics problems on Energy

• Jul 30th 2012, 01:29 AM
fActor
Physics problems on Energy
1. A stone of mass 0.5 kg is projected vertically upwards with an initial velocity of 4.0ms^-1. What is its kinetic energy when it reaches a height of 0.5m?

2. http://i48.tinypic.com/iyj0a9.png (both questions)

I couldn't load the Physics Help Forums website. Hope posting in here is just as fine, since it says in the description 'chemistry and physics'.
• Jul 30th 2012, 03:59 AM
skeeter
Re: Physics problems on Energy
use conservation of energy principles in both questions ...

Quote:

1. A stone of mass 0.5 kg is projected vertically upwards with an initial velocity of 4.0ms^-1. What is its kinetic energy when it reaches a height of 0.5m?
initial kinetic energy = gravitational potential energy + final kinetic energy

http://i48.tinypic.com/iyj0a9.png

1. initial total mechanical energy - work done by friction = final total mechanical energy

$\displaystyle mgh_A - f \cdot \Delta x = mgh_B + \frac{1}{2}mv_B^2$

solve for $\displaystyle h_B$

2. you can answer this question