Answer:
See the explanation.
Explanation:
The speeds of sound depend upon the temperature of the medium. As the temperature increased in the afternoon, the speed of sound increases. Then the time taken by reflected sound will be less than 0.1 sec in the afternoon. And to hear an echo the time gap between an original sound and reflected sound must be at least 0.1 sec. That is why the student could not hear the echo at all in the afternoon.
Answer:
2.74
Explanation:
Magnification = image distance/object distance
Mag = v/u
Given
v = 46cm
u = 16.8
Magnification = 46/16.8
Magnification = 2.74
Hence the magnification is 2.74
Answer:
v=10.75m/s
Explanation:
It is given that,
Pete drives 215 Meters in 20 seconds. He is driving down 7th floor. We need to find his speed.
Speed = distance/time
⇒
Hence, the speed of Pete is 10.75 m/s.
Answer:
Ek= 35.392 kJ or 35.392 10³ J
Explanation:
Formula for Kinetic energy:
Ek= 
× m × 
since m= 65kg and v= 33m/s
Ek= × 65×
Ek= 35.392 kJ or 35.392 10³ J
