Monday

December 22, 2014

December 22, 2014

Posted by **ShaSha** on Monday, January 6, 2014 at 5:09pm.

- physics -
**Damon**, Monday, January 6, 2014 at 5:13pmpotential energy = m g h = 3(9.81)(120)

Ke = .5 m v^2 = .5 (3)(v^2)

so

v^2 = 2 * 9.81 * 120

- physics -
**ShaSha**, Monday, January 6, 2014 at 5:34pmI am lost...please explain

- physics -
**Damon**, Monday, January 6, 2014 at 5:40pmwell, yo9u can just memorize the formula. Most of us know it.

For something dropped with no air resistance from height h

v = sqrt (2 g h)

- physics -
**ShaSha**, Monday, January 6, 2014 at 5:50pmLet me see if I get this:

KE=1/2(m)(v^2)

but because I do not know the velocity, I would use the formula v=sqrt (2 g h)

v=sqrt (2 g h)

=sqrt (2*9.8*120)

=sqrt (2352)

then I would use the velocity 2352 for the formula

KE=1/2(m)(v^2)

=1/2 (3)(2352)

KE= 3528

- physics -
**Damon**, Monday, January 6, 2014 at 6:12pmYou could do it the way I did it:

Potential energy lost = kinetic energy gained

m g h = (1/2) m v^2

g h = (1/2) v^2

2 g h = v^2

v = sqrt (2 g h)

However many students and teachers have just plain memorized

v = sqrt (2 g h)

because it is used so frequently.

- physics -
**ShaSha**, Monday, January 6, 2014 at 6:23pmThank you so very much

**Answer this Question**

**Related Questions**

chemistry - when a ball is dropped throuh a height, its potential energy changes...

physics - a ball has a mass of 0.5kg dropped from a cliff top, the ball srtikes ...

Physics - How much kinetic energy does a 1 kg ball have if it has a velocity of ...

Physics - If a .3kg arrow is fired at 120m/s at a 30degree angle with the ...

science - A bouncy rubber ball is dropped from a height of about a metre above ...

Physical Science - Four balls are taken to the top of a building. Ball 1 is ...

physics - a ball is dropped from the top of a 5m tall building. what is the ...

physics - a tennis ball is dropped from the top of 12.2 m tall building. b) how ...

PHISIC - A bouncy rubber ball is dropped from a height of about a metre above ...

physics - A ball is dropped from top of a building.if the distance travelled by ...