<span>So we want to know which of the following is the best representation of converting potential energy into kinetic energy. The correct answer is C. A roller coaster rounds a curve to climb the next hill. So before he climbed the hill, the roller coaster had kinetic energy which he used to climb to the hill. Then the potential energy he has on the hill can again be transformed into kinetic energy when he will go down hill. </span>
Answer: 12Mg/h
Explanation:
Let the spring is compressed by a distance x,before the lift stops,then
Mg(h+x)= 1/2 kx^2 ............... 1
Kx - Mg = M ( 5g ) ............ 2
Make x the subject in equation 2
Kx = 5Mg + Mg
Kx = 6Mg
x = 6Mg/k ............ 3
Put equation 3 into 1
Mg ( h + x ) = 1/2 kx^2
Mgh + Mgx = 1/2kx^2
Mgh + Mg × 6Mg/k = 1/2k × ( 6Mg/k )^2
Mgh + Mg× 6Mg/k = 1/2k 36M^2g^2/ k^2
h =18Mg/k - 6Mg/h
K = 12Mg/h
Well 200 doubled or (x2)=400 if that’s what it means
