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Mass of the roller coaster = 1000 kg
Velocity of the roller coaster = 20.0 m/s
We know the formula for finding the kinetic energy is
Kinetic energy = 0.5 * mass * (velocity) ^2
= 0.5 * 1000 * (20)^2
= 0.5 * 1000 * 400
= 200000 Joules
So the Kinetic energy of the roller coaster is 200000 joules.
Let Jeremy's age be x
if Jeremy's grandfather is four times as old as he is,grandfather's age is 4x
if the sum of their ages is 90, we have
x%2B4x=90
5x=90
x=90%2F5
x=18->Jeremy's age
Jeremy's grandfather will be 4x=4%2A18=72
answer:
D. 72
