Use the initial potential energy that you just calculated and the principle of conservation of energy to determine the kinetic energy at the lowest point in terms of mass, m. (Assume that the initial velocity of the roller coaster is zero, and ignore friction.)
The initial potential energy is 980,000N, the lowest point is 3.5 metres.

Question

Use the initial potential energy that you just calculated and the principle of conservation of energy to determine the kinetic energy at the lowest point in terms of mass, m. (Assume that the initial velocity of the roller coaster is zero, and ignore friction.) 
The initial potential energy is 980,000N, the lowest point is 3.5 metres.

jamesj · Answer

This is clearly from the middle or end of a problem.  Could you give us the complete context, so we can make sure you get the right answer?  A diagram also wouldn't hurt.

anonymous · Answer

Well the prior question was to find out the potential energy of a rollercoaster at the height of 40m weighing 2.5 tonnes, which is 980,000N. Then in this question is says to find the kinetic energy when the height is 3.5m. http://www.dreamworld.com.au/Schools/pdf/edu_Cyclone%20Student%20Activity%20Physics.pdf Page three is where the questions are.

jamesj · Answer

As you are told the KE at the top is zero, that means at the bottom the KE will be the difference in PE of the top from the bottom.  Hence find the PE(bottom) and subtract that from PE(top) to find KE.

anonymous · Answer

Ahhhh okay, thank you.