Question

A ball crosses same height at t=1sec and t=3sec .choose the correct option A.Total time of flight is4 sec. B.Total time of flight is 2sec. C.projection speed is 40m/sec D.projection speed is 20m/sec

Answer 1

Answer:

It means it took 1 second to reach from A to B.

Due to symmetry it will take 0.5 second to reach from A to C.

Hence total time to reach from ground to C = 4+0.5=

2

9

sec

Maximum height =

2

1

×g×(

2

9

)

2

=101.25m

Length covered from C to B =0+

2

1

×g×(

2

1

)

2

=1.25m

∴ h = Maximum height - CB

=101.25−1.25=100m

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