Answer:
Explanation:
We shall apply Doppler's effect here .
original frequency = 79.79 kHz
apparent frequency due to movement of source ( bat ) = 81.63 Hz
Let the velocity of bat be v .
expression for apparent frequency can be given as follows
n = 
n is apparent frequency , n₀ is original frequency , V is velocity of light and v is velocity of source of sound
Putting the values
81.63 = 
340-v = 332.33
v = 7.67 m /s
velocity of bat is 7.67 m /s .
Answer:
170 N
Explanation:
Since Force F = ma were m = mass = 85 kg and a = acceleration = 2.0 m/s².
So the net force on the bicycle is
F = ma = 85 kg × 2.0 m/s² = 170 N
F-free = m*g - F_air = m*a
F_air = 1.2 * m
a= (105 kg * 9.8 m.s^2 - 5*105) / 105 kg
a = 9.3 m/s
Hope this helps