Answer:
Stretch can be obtained using the Elastic potential energy formula.
The expression to find the stretch (x) is 
Explanation:
Given:
Elastic potential energy (EPE) of the spring mass system and the spring constant (k) are given.
To find: Elongation in the spring (x).
We can find the elongation or stretch of the spring using the formula for Elastic Potential Energy (EPE).
The formula to find EPE is given as:

Rewriting the above expression in terms of 'x', we get:

Example:
If EPE = 100 J and spring constant, k = 2 N/m.
Elongation or stretch is given as:

Therefore, the stretch in the spring is 10 m.
So, stretch in the spring can be calculated using the formula for Elastic Potential Energy.
Answer:
It covers distance of 9.15 football fields in the said time.
Explanation:
We know that

Thus distance covered in blinking of eye =

Thus no of football fields=
The modern name, Mount St. Helen's, was given to the volcanic peak in 1792 by seafarer and explorer Captain George Vancouver of the British Royal Navy. He named it in honor of fellow countryman Alleyne Fitzherbert, who held the title 'Baron St. Helen's.
The only force applied is gravity
Answer:
Explanation:
We shall apply law of conservation of momentum during the collision of ball A and B .
Total momentum before collision of A and B = .35 x 10 = 3.5 kg m/s
Let the velocity of B after collision be v .
Total momentum after collision = .35 x 2 + .35v
According to law of conservation of momentum
.35 x 2 + .35v = 3.5
.35 v = 2.8
v = 8 m /s .
The direction of B will be same as direction of A .