Gravity, and Normal. Check the comments for why Applied isn't one.
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Answer:
37.42 m/s
Explanation:
We know that apparent frequency, 
is given by
where f is the given frequency in this case 392, V is the speed of sound in air which is given as 343 and 
is the speed of car which is unknown, \bar f is given as 440 Hz
Answer:
When you have to do an English-Metric (SI) length conversion, and you already know the English units of length (miles, yards, feet, inches, etc.), all you need to remember is one simple relationship, and you can readily convert any length in the SI system, to the equivalent length in the other.
1 foot (ft) = 0.3048 meters (m)
BIn this case you need your answer in inches. You (hopefully) know there are 12 inches in a foot, so you just do the following:
1 inch (in) = 1/12 ft = 0.3048/12 m = 0.0254 m
Answer:
D
Explanation:
D) The overall work done by gravity is zero
This statement is correct .
If m be the mass of each of the children and h be the height of tower
work done by gravity on the boys in going up = - mgh
it is so because force applied by gravity = mg downwards and displacement
is upwards
work done will be negative = - mgh
Work done by gravity on boys when they come down = + mgh because both force and displacement are downwards .
Hence total work done = - mgh + mgh = 0.
The children will have same kinetic energy as the inclined surface is friction-less so no energy will be dissipated hence addition of energy to boys in both the cases will be same.
