Answer:
Repulsion is the sure test for magnetism because it occurs only when two like poles of a magnet exist while the attraction phenomenon can occur between two unlike poles of a magnet and also between a magnet and a magnetic material means if there are two magnets they will attract each other and suppose if one material
In a quarter of an hour it will travel 1/4 x 90 = 22.5Km
The formula for kinetic energy is KE = (1/2) (mass) (speed²)
== The 50 kg ball traveling at 10 m/s has <em>some</em> kinetic energy.
== A 50 kg ball traveling at 20 m/s would be moving at double the speed. So it would have (2)² = <em>4 times as much</em> kinetic energy.
== A 50 kg ball traveling at 5 m/s would be moving at 1/2 the speed. So it would have (1/2)² = <em>1/4 as much</em> kinetic energy.
== A 50 kg <u>person</u> falling at 10 m/s would have <em>exactly the same</em> amount of kinetic energy as the 50 kg <u>ball</u> traveling at 10 m/s.
Wave speed of a wave = wave length * frequency
0.50 m * 100 Hz = 50 m/s
