A family uses 8 kW of power:- Direct solar energy is incident on the horizontal surface at an average rate of 200 W per square meter. If 20% of this energy can be converted to useful electrical energy, how large an area is needed to supply 8 kW?

A person trying to lose weight (dieter) lifts a 10 kg mass, one thousand times, to a height of 0.5 m each time. Assume that the potential energy lost each time she lowers the massis dissipated:- Fat supplies 3.8 xx 10^7J of energy per kilogram which is converted to mechanical energy with a 20% efficiency rate. How much fat will the dieter use up?

Jagriti designed an atomic power which produces 200 MW power by using "_92U^235 . If fission of each atom of "_92U^235 produces 200 MeV of heat energy and the plant converts 80% of it into electric energy then how many grams of "_92U^235 will be consumed by that plant in a day.

Suppose India had a target of producing by 2020 AD, 200,000 MW of electric power, ten percent of which was to be obtained from nuclear power plants. Suppose we are given that, on an average, the efficiency of utilization (i.e. conversion to electric energy) of thermal energy produced in a reactor was 25%. How much amount of fissionable uranium would our country need per year by 2020? Take the heat energy per fission of "^235U to be about 200MeV.

Munish designed an atomic power plant which produces 250 MW power by using "_92U^235 . If fission of each atom of "_92U^235 produces 200 MeV of heat energy and the plant converts 75% of it into electric energy then how many grams of "_92U^235 will be consumed at that plant in a day ?

Aman designed an atomic power plant which produces 100 MW power by using "_92U^235 . If fission of each atom of "_92U^235 produces 200 Me V of heat energy and the plant converts 90% of it into electric energy then how many grams of "_92U^235 will be consumed at that plant in a day ?

How much mass of _92 U^235 is converted into energy per day at a nuclear power plant operated at 10^6 kW ?

An electric refrigerator rated 500 W operates 24 hours/day. What is the cost of the energy to operate it for 20 days at Rs.2.00 per kWh?