Question

Name the instrument which is used to measure the instantaneous speed of a vehicle.

Read the given passage and answer the questions that follow based on the passage and related studied concepts. A bus is moving with a velocity of 50 km/h. The driver sees a child running across the road and he pressed the brakes. The time taken by him to stop the bus in this emergency was 1/10 th of a second. In a second case, another bus was coming on the same road at the same 50 km/h and the driver saw another child crossing the road. He applied the brakes and time taken by him to the emergency was 0.5 sec. Both the buses started moving to their destination after 10 minutes. Bus A moved at 45 km/h while bus B moved at 60 km/h.