A 6.0kg block is released from rest 80m above the ground. When it has fallen 60m its kinetic energy is:
I got 1200J as my answer
mgh=(6.0*9.81* 60m)=3531.6
PE + KE= (ME + KE)
3531.6 + KE= (6.0*9.81*80m)
KE= 1177.2
is that right

A 6.0 Kg block is thrown up from a point 20m above Earth's surface. At what heights above Earth's surface will the gravitational potential energy of the earth-block system have increase by 500J.
mgh= 2(9.81)(20m)= 392.4 --> potential
500J= mgh
500J = (2kg)(9.81) (h)
h= 25m
someone had told me my actual answer for height should be 45m, because I need to add the 20 I started with.

Thank you

The KE falling sixty meters is 3500J, as you calculated It lost that much gravitational PE, so it is transformed to KE.
If you wnat to do it this way
PE + KE= (ME + KE)
PE(at20) + KE(at20)= (6.0*9.81*80m)
mg20 +KE(at20)= (6.0*9.81*80m)
and solve for KE at 20 , it will be the same as above.

Second question.
mg(distanceup )=500
YOu do not add the 20, because the problem is dealing with INCREASE in PE, not total PE.

1. 👍 0
2. 👎 0
3. 👁 309

## Similar Questions

1. ### physics

3 kg block (block A) is released from rest at the top of a 20 m long frictionless ramp that is 5 m high. At the same time, an identical block (block B) is released next to the ramp so that it drops straight down the same 5 m. Find

asked by Katelyn on October 25, 2016
2. ### physics

A 3 kg block (block A) is released from rest at the top of a 20 m long frictionless ramp that is 5 m high. At the same time, an identical block (block B) is released next to the ramp so that it drops straight down the same 5 m.

asked by Katelyn on November 2, 2016
3. ### physics

In the following figure m_1 = 20.0kg kg and á alpha = 50.9 ∘ ^\circ. The coefficient of kinetic friction between the block and the incline is ì k = 0.40 What must be the mass m 2 of the hanging block if it is to descend 9.00m

asked by Bob on July 4, 2013
4. ### physics

In the Figure the pulley has negligible mass, and both it and the inclined plane are frictionless. Block A has a mass of 1.3 kg, block B has a mass of 2.7 kg, and angle è is 26 °. If the blocks are released from rest with the

asked by chirayu on March 23, 2009
5. ### physics

In the Figure the pulley has negligible mass, and both it and the inclined plane are frictionless. Block A has a mass of 1.3 kg, block B has a mass of 2.7 kg, and angle è is 26 °. If the blocks are released from rest with the

asked by sweety on March 21, 2009
6. ### physics

A 0.145 kg block is released from rest from the top of a 51.7◦ frictionless incline. When it has fallen a vertical distance of 1.3 m, a 0.00794 kg bullet is fired into the block along a path parallel to the slope of the incline,

asked by Jen on April 9, 2010
7. ### Physics

A 2.0kg block hang from a vertical spring causes it to stretch by 200cm. If the 2.0kg block is replaced by a 0.50kg mass and the spring is stretched and released, what are the frequency and period of the oscillations? Please help

asked by Ellie on January 22, 2013
8. ### physics

In the Figure the pulley has negligible mass, and both it and the inclined plane are frictionless. Block A has a mass of 1.3 kg, block B has a mass of 2.7 kg, and angle è is 26 °. If the blocks are released from rest with the

asked by sweety on March 22, 2009
9. ### physics

a 4.0kg block of wood is pulled along a horizontal ground from rest and a force of 15N is required to produce acceleration of 2.0metres per second squared . what should the magnitude of the force be in order to pull the block of

asked by Nicole on August 22, 2018
10. ### physics

In the Figure the pulley has negligible mass, and both it and the inclined plane are frictionless. Block A has a mass of 1.3 kg, block B has a mass of 2.7 kg, and angle è is 26 °. If the blocks are released from rest with the

asked by nicks on March 22, 2009

More Similar Questions