Answer:
(a) 8 m/s
(b) 5 s
Explanation:
(a)
Using,
V² = U²+2gh ......................... Equation 1
Where V = final velocity, U = Initial velocity, g = acceleration due to gravity on the surface of the moon, h = height reached.
Given: V = 0 m/s ( At it's maximum height), g = -1.6 m/s² ( as its moves against gravity), h = 20 m.
Substitute into equation 1
0 = U²+[2×20×(-1.6)]
-U² = - 64
U² = 64
U = √64
U = 8 m/s.
(b)
V = U +gt.................... Equation 2
Where t = time to reach the maximum height.
Given: V = 0 m/s ( At the maximum height), g = -1.6 m/s² ( Moving against gravity), U = 8 m/s.
Substitute into equation 2
0 = 8+(-1.6t)
-8 = -1.6t
-1.6t = -8
t = -8/-1.6
t = 5 s.
at any angle between -90 and 90 degrees. In the diffused reflection ,the surface is rough and the direction of light in not the same as the incident light. It can be reflected at any angle
Level of sound is related to intensity by this equation

given that
L = 85 dB
also we know that

now we have

By solving above equation


now above is the intensity due to two firecrackers and if we wish to find the sound level of one firecracker then we will find its half level intensity


now again by above formula


Answer:
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