Advertisements
Advertisements
प्रश्न
A car travels from P to Q at a uniform speed of 20 ms-1 and immediately turns back and travels towards Q with a uniform speed of 30 ms-1. What is the average speed for the whole journey?
Advertisements
उत्तर
let distance between P and Q is S.
Speed of car while travelling from P to Q is 20 m/s.
Let car take time T1 to travel from P to Q then T1= S/20.
Speed of car while travelling from Q to P is 30 m/s.
Let car take time T2 to travel from Q to P then T2= S/30.
Total time = T1 + T2 = S/20 +S/30 =S/12.
So average speed of journey = total distance/ total time = 2S/(S/12) = 24 m/s.
Average speed of journey is 24 m/s.
APPEARS IN
संबंधित प्रश्न
What do you understand by the average speed of a body?
Do speed and average speed of a body have the same meaning?
Which is greater?
(i) 36 km/hr
(ii) 8.5 m/s
A girl had designed a clap switch for a science exhibition that enabled her to switch on or off an alarm just with clapping of hands. While testing her device in a hall, she noticed that once the alarm has sounded it followed with another one due to echo of the clap, that is, the sound reflected by the walls. She recorded the two soundings of alarm with her tape recorder and found out that time difference in between them is 0.1 s. If the distance of the walls be 15 m, calculate the speed of sound.
The correct relation among the following is
Distances between two cities are measured in kilometres.
Which of the quantities have the same SI unit?
______ measures the instantaneous speed of the automobile.
Assertion: The speed of a body can be Negative.
Reason: If the body is moving in the opposite direction of positive motion, then its speed is Negative.
Distinguish between Speed and velocity.
