Which part of the earth is considered to be the center

Postal worker on a bicycle travels at an average speed of 4m/s for 3 minutes. Work out how far she travelled.

A 4.3-g object moving to the right at 22 cm/s makes an elastic head-on collision with a 8.6-g object that is initially at rest. what is the velocity of the 4.3-g mass after the collision?

During refraction, what happens to a wave when it travels from one medium to another? The wave travels in the opposite direction. The wave changes speed. The wave moves in the same direction. The wavelength increases.

The energy in a wave travels a) up and down b) backward c) forwards d) waves do not carry energy

An ice sheet 5m thick covers a lake that is 20m deep. what is the temperature of the water at the bottom of the lake? explain your answer. coefficient of volume expansivity at 20 degree centigrade is 2.1x10^-4

Animals that can hear ultrasonic sounds are the what

If the rock has a mass of 1 kg which is the speed of the rock after it has fallen for two seconds

2 Cars A and B both at rest are to set of from a town to a common destination along the same route. Car A was the first to take off and travelled at 2.

In an experiment to measure the acceleration due to gravity, g two values, 9.72 m/s2 and 9.67 m/s2, as determined. if the accepted value of g is: 9.8 m/s2 find the followings: i) the percentage difference of the measurements?

If momentum is conserved in a collision, does this indicate conclusively that the collision is elastic?