Answer:
(A) Torque required is 21.205 N-m
(b) Wok done will be equal to 1199.1286 j
Explanation:
We have given moment of inertia 
Wheel deaccelerate from 135 rpm to 0 rpm
135 rpm = 
Time t = 8 sec
So angular speed
and 
Angular acceleration is given by 
Torque is given by torque 

Work done to accelerate the vehicle is


Answer:
f=896Hz
Explanation:
Given data
Vs(speed of the ambulance)={(104 km/h)*(1000m*(1 h/3600)}=28.9m/s
f(frequency of the ambulance siren)=821 Hz
v(speed of sound)=345 m/s
Vo(speed of the observer)=0 m/s
To find
f(The ambulance is approaching the person)
Solution
From Doppler effect

As the ambulance approaches the we assign a positive sign for speed "vs" of the ambulance
So

Substitute the values from given data

Answer: yes wave are created by vibration because if there anit any vibration then the water cant move
Explanation:
Changing the medium of the wave.
Waves is always determined by the properties of the medium, which means that changing the medium will change the velocity of the wave