On a planet far, far away, an astronaut picks up a rock. The rock has a mass of 4.80 kg , and on this particular planet its weight is 41.5 N . You may want to review (Pages 121 - 129) . Part A If the astronaut exerts an upward force of 48.1 N on the rock, what is its acceleration

   a = 1,375 m / s²

Explanation:

For this exercise we use Newton's second law where the force applied by the astronaut is F = 48.1, the body weight is W = 41.5 N and the body mass is m = 4.80 kg

              F - W = m a

              a = (F -W) / m

let's calculate

              a = (48.1 - 41.5) / 4.80

              a = 1,375 m / s²

this acceleration is directed upwards

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