Ans 7:
Class : Class 7
Time taken to shoot 10 images is 1 secTime taken to shoot 6 images is 0.6 sec.Assuming that the full revolution of ball is not considered thenSpeed = distance/time= 15/0.6= 25m/sIf we consider that in five shots the ball has exactly done two revolution then we have to also consider that it has travelled only 12.5 MTS.Then the speed is 12.5/0.5=25 m/s
Ans 8:
Class : Class 7
time taken to shoot 10 images=1 second.time taken to shoot 5 images=5/10=1/2seconds.speed=distance/time=15divided by 1/2=15*2=30m/s
Ans 10:
Class : Class 7
Given ..
(1) time taken to take 10 shots=1 sec
==> time taken to take one shot= 1/10 sec
(2) Distance travelled by ball while camera took 6 shots =15 meter
We know , speed= distance/time
Distance=15m
Time= Not known... lets find out the time to take six shots
Fist shot was taken after = 0sec (as first short was taken at beginning)
Second shot taken after = 1*(1/10) = 1/10 seconds
Third short taken after = 2*(1/10) =2/10 seconds
Similarly .. sixth shot taken after = 5*(1/10) =5/10
Now..
speed = distance/time = 15 / (5/10) = 30 m/second
Hope, it helps.
Ans 17:
Class : Class 8
thanks kashvi I now really understand how to solve these type of questions . Very good explanation.