4. A source of sound frequency 600Hz is placed inside water. The speed of sound in water is 1500 ms and in air is 300 ms. The frequency of sound recorded by an observer, who is
standing in air, is

Ascrew incorporates which other simple machine? lever wheel and axle inclined plane pulley

Under the action of a constant force an object accelerates at 7.8 m/s2. what will the acceleration be if (a) the force is halved? (b) the object's mass is halved? (c) the force and the object's mass are both halved? (d) the force is halved and the object's mass is doubled?

When a pair of 10-n forces act on a box of candy, the net force on the box is a 20 n. b about 14 n. c zero. d any of the above depending on the directions of forces.