I think it would be E. The higher the object the less wavelength is possible.
Answer:The frequency of the echo is slightly decreased
Explanation:
Given
speed of boat 
cliff is
away
when boat is still , suppose t is the time taken by the echo to reach observer on the boat
But as soon as boat starts moving the distance between cliff and boat decreasing and time for echo to reach observer also decreases
and we know 
therefore frequency of the echo slightly decreased.
Answer:
W = 1094100 [lb*ft]
Explanation:
We recall the definition of work which says that work is equal to the product of force by distance. We have the weight data of the ball and cable.
30[ft] * 7[lb/ft] = 210 [lb]
the force combined will be:
F = 210 + 5000 = 5210[lb]
W = 5210 * 30 = 1094100 [lb*ft]
To solve this problem we will apply Newton's second law, which indicates that the force is equivalent to the product between mass and acceleration, so

Here,
F= Force
m = Mass
a = Acceleration
Rearranging to find the mass we have,

The value of the acceleration is


Replacing to find the mass,



Now in ponds this value is


Therefore the mass of the spacecraft is 52.8lb