Matter in Our Surroundings — Science STD 9 — Question

Define velocity. What is the SI unit of velocity?

Which postulate of Dalton’s atomic theory is the result of law of conservation of mass given by Lavoisier?

How much momentum will a dumb-bell of mass 10kg transfer to the floor if it falls from a height of 80cm? Take its downward acceleration to be 10m s^-2.

A car is moving on a level road. If the driver turns off the engine of the car, the car’s speed decreases gradually and ultimately it comes to a stop. A student says that two forces act on the car which bring it to a stop. What could these forces be? Which of these two forces contributes more to slow down and stop the car?

Name the following:

1. Cavity present in the body of sponges.
2. Cavity present in the body of cnidarians.

A stone is thrown in a vertically upward direction with a velocity of 5ms^-1. If the acceleration of the stone during its motion is 10ms^–2 in the downward direction, what will be the height attained by the stone and how much time will it take to reach there?

The maximum speed of a train is 80km/h. It takes 10h to cover a distance of 400km. Find the ratio of its maximum speed to its average speed.