The echo of a sounder from the bottom of an ocean is heard 2.5 seconds later. If the speed of sound in water is 1,400ms^-1, the depth of the ocean is

An electric iron is rated at 1000watts, 250v. The corresponding maximum resistance and accompanying current is

The force responsible for holding the moon in its orbit around the earth against the gravitational pull of the earth is

A mango fruit drops from a branch 10m above the ground, just before hitting the ground its velocity is (g = 10ms^-2)

Which of the following machines does NOT apply the lever principle?