Trolleys X and Y of masses m and 3m respectively are travelling at the same speed towards each other. The trolleys collide and move off together. Choose the correct answer.

Ahypothesis is? close agreement by competent observers of observations of the same phenomena. a guess that has been tested over and over again and always found to be true. an educated guess that has yet to be proven by experiment. the long side of a right triangle. a synthesis of a large collection of information that includes guesses.

Complete the statement about memory improvement. ( )involves organizing and breaking down information into easier groups to expand capacity. rehearsal is the verbal repetition of information. these techniques are especially important for the improvement of ( ) memory.

Ihave a density of 1.61g/cm^3 and a mass of 28g. find the missing value