# PhysicsWatch

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#1
Guys help me in this pls
A roller coaster train has a mass of 1500'kg, it descends from point p which is 30m above the ground to point Q which is 10 m above the ground
a) calculate the loss in gravitational potential energy of the train when it moves from point p to Q
B) if 20% of the gravitational potential energy lost is dissipated calculate the speed of the train at point Q and the kinetic energy of the train at pony Q
Plsssss solve this I can't seem to solve it
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2 years ago
#2
Do you know how to calculate gravitational potential energy?
, where is mass, is height and is acceleration due to gravity, which is taken as at GCSE level.

So the loss in GPE will be equal to GPE at the top minus GPE at the bottom.

Then for part b), the loss in GPE = gain in KE + heat dissipated, because of conservation of energy.

Kinetic energy is given by , where is mass and is speed.

Have a go and let us know how you get on
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