Advertisements
Advertisements
प्रश्न
A boy covers half of his journey with a uniform speed of u and the other half with a uniform speed of v. What is the average speed for the whole journey?
Advertisements
उत्तर
Let total distance be S.
Boy covers distance S/2 with speed u then time taken by him to cover this distance would be T1 =S/2u.
Again boy covers rest of the distance S/2 with speed v then time taken by him to cover this distance would be T2 =S/2v.
So total time taken by boy to cover the distance S is T = T1 + T2.
Total time T= S/2 (1/u +1/v) = s(u+v)/2uv.
And average speed = S/T = 2uv/(u+v).
APPEARS IN
संबंधित प्रश्न
If a body traverses a distance in direct proportion to the time, the speed of the body is ______.
What do you understand by the average speed of a body?
Which is greater?
(i) 36 km/hr
(ii) 8.5 m/s
The relation S= v x t can easily be used to find the tota l distance covered by a body moving with non -uni form speed. (Yes/ no)
The average time taken by a normal person to react to an emergency is one fifteenth of a second and is called the 'reaction time'. If a bus is moving with a velocity of 60 km/h and its driver sees a child running across the road, how much distance would the bus had moved before he could press the brakes? The reaction time of the people increases when they are intoxicated. How much distance had the bus moved if the reaction time of the driver were 1/2 s under the influence of alcohol?
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.
Length of scale : metre :: Speed of aeroplane : ______.
A bus travels 54 km in 90 minutes. The speed of the bus is ______.
Why did the actual speed differ from the average, speed?
In a 100m race, the winner takes 10s to reach the finishing point. The average speed of the winner is ______.
