Aball is thrown straight up from the edge of the roof of a building of height 60.0m. a second ball is dropped from the roof 2s later. what must be the initial speed of the first ball if both are to hit the ground at the same time?

u = 15.99 m/s

Explanation:

Given that

h= 60 m

For second ball

Lets take after t time after second ball hit the ground

Here u = 0 m/s

t=3.49 s

So the time taken by first ball will be 3.49 + 2 = 5.49 s

For first ball

u = 15.99 m/s

So the initial velocity of first ball will be 15.99 m/s

specific latent heat of fusion, lf, of a substance is defined as the amount of heat required to change a unit mass of the substance from solid to liquid state, without any change in the temperature.

explanation:

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.