The answer is A. Force is equal to mass x acceleration. The acceleration due to gravity is a constant so multiplying the mass by 2 would double the force.
Explanation:
Echoes occur due to the reflection of sound from any obstacle, but not all the reflected sound waves lead to the phenomenon of echo. For the echo to be heard it actually depends upon the human perception as well, human ears can encounter the difference between the sound wave directly form the source and the reflected sound waves only if there is a minimum time gap of one-tenth of a second. For this time gap in the atmosphere at normal temperature and pressure the obstacle must be at least 7 meters away from the sound source.
Taha xain malai ..........hhdd
electromagnet
When a electric current is passed through an insulated wire that is coiled around an iron core, like a nail, an electromagnet is created.
A discovery not the others
