A 1.2 W point source emits sound waves isotropically. Assuming that the energy of the waves is conserved, find the intensity (a)1.6 m from the source and (b)2.2 m from the source.

(a)

(b)

Explanation:

Given:

Point source

Distance from source Part a

Distance from source Part b

Solution:

Part (a)

Using intensity formula at distance L from an isotropic point.

 -------------------(1)

Substitute and in equation 1..

Part (b)

Substitute and in equation 1.

Therefore, the intensity at distance 1.6 m from the source:

.

And, the intensity at distance 2.2 m from the source:

.

convex lenses are thicker at the middle. rays of light that pass through the lens are brought closer together (they converge). a convex lens is a converging lens. when parallel rays of light pass through a convex lens the refracted rays converge at one point called the principal focus.

the small 0.38-kg slider is known to move from position a to position b along the vertical-plane slot. determine (a) the work done on the body by its weight and (b) the work done on the body by the spring. the distance r = 0.70 m, the spring modulus k = 154 n/m, and the unstretched length of the spring is 0.53 m

explanation:

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