A 1055-kg van, stopped at a traffic light, is hit directly in the rear by a 660-kg car traveling with a velocity of 2.00 m/s. Assume that the transmission of the van is in neutral, the brakes are not being applied, and the collision is elastic. What is the final velocity of each vehicle

Explanation:

According to law of conservation of energy

m1u1 + m2 u2 = (m1+m2)v

m1 and m2 are the masses of the bodies

u1 and u2 are the initial velocities

v is the final velocity after collision

Substitute the given values into the formula

1055(0) + 660(2) = (1055+660)v

0+1320 = 1715v

v = 1320/1715

v = 0.77m/s

Hence the final velocity of each vehicle is 0.77m/s

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form