f' = frequency observed by the police car after sound reflected from the vehicle and comes back to police car = 1250 Hz
f = frequency emitted by the police car = 1200 Hz
V = speed of sound = 340 m/s
v = speed of vehicle = ?
frequency observed by the police car is given as
f' = f (V + v)/(V - v)
inserting the values in the above equation
1250 = 1200 (340 + v)/(340 - v)
v = 6.9 m/s
Answer:
Voltage in primary coil is 3.91 V
Explanation:
For transformer we know that the working principle is given as

here we know that
![V_1 [tex] = voltage in primary coil[tex]V_2 = 25 V](https://tex.z-dn.net/?f=V_1%20%5Btex%5D%20%3D%20voltage%20in%20primary%20coil%3C%2Fp%3E%3Cp%3E%5Btex%5DV_2%20%3D%2025%20V)


Now we have


Given:
mass is 3.1 kilograms
The acceleration due to gravity
is 9.8m/s2
Required:
Weight
Solution:
W = mg
W = (3.1 kilograms)( 9.8m/s2)
W = 30.38 Newtons
Answer:r=5.824 mm
Explanation:
Given
Charge 

Force between them 
Electrostatic Force is given by

where
and
are the charge on the Particles
r=distance between them




