A vacuum cleaner standing on the floor turns through a small angle when switched on and then stops. Why does this happen?

When a plane mirror is rotated through an angle theta then the reflected ray turns through the angle 2 theta then the size of the image

When a copper coin is dipped in silver nitrate solution, a glitter appears on the coin after some time. Why does this happen? Write the chemical equation.

Two rings are suspended from the points A and B on the ceiling of a room with the help of strings of length 1.2 m each as shown. The points A and B are separated from each other by a distance AB = 1.2 m. A boy standing on the floor throws a small ball so that it passes through the two rings whose diameter is slightly greater than the ball. At the moment when the boy throws the ball, his hand is at a height of 1.0 m above the floor. A stop watch which is switched on at the moment of throwing the ball reads 0.2 s when the ball passes through the first ring and 0.6 s when it passes through the second ring. When the ball lands on the floor, the stop watch reads:

Two rings are suspended from the points A and B on the ceiling of a room with the help of strings of length 1.2 m each as shown. The points A and B are separated from each other by a distance AB = 1.2 m. A boy standing on the floor throws a small ball so that it passes through the two rings whose diameter is slightly greater than the ball. At the moment when the boy throws the ball, his hand is at a height of 1.0 m above the floor. A stop watch which is switched on at the moment of throwing the ball reads 0.2 s when the ball passes through the first ring and 0.6 s when it passes through the second ring. The maximum height attained by the ball above the floor is:

Two rings are suspended from the points A and B on the ceiling of a room with the help of strings of length 1.2 m each as shown. The points A and B are separated from each other by a distance AB = 1.2 m. A boy standing on the floor throws a small ball so that it passes through the two rings whose diameter is slightly greater than the ball. At the moment when the boy throws the ball, his hand is at a height of 1.0 m above the floor. A stop watch which is switched on at the moment of throwing the ball reads 0.2 s when the ball passes through the first ring and 0.6 s when it passes through the second ring. The ball lands on the floor at a distance: