Answer:
Explanation:
Given
mas of car=870 kg
coffee mug mass=0.47 kg
coefficient of static friction between mug and roof 
Coefficient of kinetic Friction 
maximum car acceleration is 
here coefficient of static friction comes in to action because mug is placed over car . If mug is moving relative to car then \mu _k is come into effect

Answer:
here as we increase the distance the intensity will decrease and hence the amplitude of the electric field will decrease and vice-versa
Explanation:
As wee know that the amplitude of the wave will decide the energy of the wave
Here we know that energy density of electromagnetic wave is given as

now we have

so here we can say that intensity of the wave at the given distance from the source is given by formula

so here as we increase the distance the intensity will decrease and hence the amplitude of the electric field will decrease and vice-versa.
Answer:
40 Hz
Explanation:
f = 1/T = 1 / 0.025 = 40 Hz