PART - 1 CH - 4 Laws of Motion — Physics STD 11 Science — Question

The sign of work done by a force on a body is important to understand. State carefully if the following quantities are positive or negative:
Work done by gravitational force in the above case.

Calculate the time required to heat 20kg of water from 10°C to 35°C using an immersion heater rated 1000W. Assume that 80% of the power input is used to heat the water. Specific heat capacity of water = 42000J kg^-1 K^-1.

Stainless steel cooking pans are preferred with extra copper bottom. Why?

A simple pendulum is inside a space craft. What should be its time period of vibration?

What energies are there in a flowing liquid?

Two artificial satellites, one of mass 400kg and another of mass 2500kg, are set in the same orbit around a planet. What is the ratio of their (i) orbital velocities, (ii) time periods?

Why does the speed of sound differ from a solid and a liquid medium of same length?

Why does a pilot not fall down when his aeroplane takes a vertical loop?

Which of the following examples represent periodic motion?
A freely suspended bar magnet displaced from its N-S direction and released.