Bats can know about their prey at a distance even in the night by emitting

The ceilings of a concert hall are generally curved

An electric heater is rated 1500 watt. If electric power costs Rs 2 per kilo-watt-hour, then the cost of power for 10 hours running of the heater is

Suppose we have an iron nail and an iron ball of same mass. When submerged in water, the iron ball may float but the nail always sinks. This is because

 
The plot given above represents the velocity of a particle (in m/s) with time (in seconds). Assuming that the plot represents a semi-circle distance traversed by the particle at the end of 7 seconds is approximately

What should be the reading of the voltmeter in the circuit given above? (All the resistances are are equal to 1 Ω and the battery is of 1.5 volt)