<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:
a

b

Explanation:
From the question we are told that
The child's weight is 
The length of the sliding surface of the playground is 
The coefficient of friction is 
The angle is 
The initial speed is 
Generally the normal force acting on the child is mathematically represented as
=> 
Note 
Generally the frictional force between the slide and the child is

Generally the resultant force acting on the child due to her weight and the frictional force is mathematically represented as

Here F is the resultant force and it is represented as 
=> 
=> 
=> 
=>
So

=> 
Generally the heat energy generated by the frictional force which equivalent tot the workdone by the frictional force is mathematically represented as

=> 
=> 
Generally from kinematic equation we have that

=> 
=> 
=> 
Answer:
Explanation:
Given that,
5J work is done by stretching a spring
e = 19cm = 0.19m
Assuming the spring is ideal, then we can apply Hooke's law
F = kx
To calculate k, we can apply the Workdone by a spring formula
W=∫F.dx
Since F=kx
W = ∫kx dx from x = 0 to x = 0.19
W = ½kx² from x = 0 to x = 0.19
W = ½k (0.19²-0²)
5 = ½k(0.0361-0)
5×2 = 0.0361k
Then, k = 10/0.0361
k = 277.008 N/m
The spring constant is 277.008N/m
Then, applying Hooke's law to find the applied force
F = kx
F = 277.008 × 0.19
F = 52.63 N
The applied force is 52.63N