Friction — Physics STD 11 Science — Question

Raindrops of radius 1mm and mass 4mg are falling with a speed of 30m/s on the head of a bald person. The drops splash on the head and come to rest. Assuming equivalently that the drops cover a distance equal to their radii on the head, estimate the force exerted by each drop on the head.

The nucleus is at rest in the laboratory frame of reference. Show that if it disintegrates into two smaller nuclei, the products must be emitted in opposite directions.

Which of the length measurements is the most accurate and why?

1. 500.0cm.
2. 0.0005cm.
3. 6.00cm.

For which condition, the distance and the magnitude of displacement of an object have the same values?

Write an expression for the velocity of the centre of mass of particles.

At Deoprayag (Garhwal, UP) river Alaknanda mixes with the river Bhagirathi and becomes river Ganga. Suppose Alaknanda has a width of 12m, Bhagirathi has a width of 8m and Ganga has a width of 16m. Assume that the depth of water is same in the three rivers. Let the average speed of water in Alaknanda be 20km/h and in Bhagirathi be 16km/h. Find the average speed of water in the river Ganga.

What is the apparent weight felt by a person in an elevator, when it is accelerating: (i) upward (ii) downward?

What range of forces are inter-molecular force?

Water is slowly coming out from a vertical pipe. As the water descends after coming out, its area of cross-section reduces. Explain this on the basis of the equation of continuity.