Answer:
-3.396 m/s or 3.465 m/s
Explanation:
v = Speed of sound in air = 343 m/s
= Relative speed of the singer
f = Observed frequency
f' = Actual frequency
1% change can mean 
From the Doppler effect equation we have

The velocity is -3.396 m/s
when 

The velocity is 3.465 m/s
Answer:
2.5 ohm
Explanation:
R' and R''' are parallel
So,
1/R1= 1/R' + 1/R'''
1/R1 = 1/2 + 1/2
1/R1 = 1
so,
R1= 1 ohm
Now R1 and R'' are in series
so,
R= R1 + R''
R= 1 + 1.5
R= 2.5 ohm
Answer:
100
Explanation:
Momentum (P) = Mass (M) × Velocity (V)
Momentum = 25kg × 4.0m/s
Momentum = 100kg m/s