A man runs with speed 54 km/hr in a straight path starting from A at 8 AM for 35 minute. What should be his speed for rest of the motion, completing 100 kms from A to B upto 9 AM.

A car start with a velocity 20 km/hr and after every hour its speed increases by 10 km/hr.
After 8 hour it starts decreasing the speed 10 km/hr after every hour and finally it stops in the destination.
What is the total length of the journey?

A helium balloon leaves the ground at a point A and rises vertically at uniform speed.
At the end of 5 minutes, Rohan finds the angular elevation of the balloon as 30 degree.
If the point at which Rohan is standing is 550 m away from point A, what is the speed of the balloon in m/s?