Explanation:
study of social sciencake us an effcient citizen of a democracy ,and it also help us to solve the practical problem in our daily life.
Newton's second law states that the force applied to an object is equal to the product between the mass m of the object and its acceleration a:

Using

and

, we can find the value of the force applied to the roller-blade to obtain this acceleration:
W = 1/2k*x^2.
k = spring constant = 2500 n/m.
x = distance = 4 cm = 0.04m (convert to same units).
W = 1/2(2500)(0.04)^2 = 2J.
<span>D) Electromagnetic radiation travels in the form of longitudinal waves.</span>