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1. At a given instant in time, a 14-kg rock that has been dropped from a high cl

ID: 2127472 • Letter: 1

Question

1. At a given instant in time, a 14-kg rock that has been dropped from a high cliff experiences a force of air resistance of 40 N. What are the magnitude and direction of the acceleration of the rock? (Do not forget the gravitational force!)


magnitude ________ m/s?

direction _____downward/upward_____?


2. A 7.0-kg block being pulled across a table by a horizontal force of 55 N also experiences a frictional force of 10 N. What is the acceleration of the block?

_______ m/s2?


3. An upward force of 45 N is applied via a string to lift a ball with a mass of 2.5 kg.

(a) What is the net force acting upon the ball?

magnitude __________?

direction __downward/upward________?


(b) What is the acceleration of the ball?

magnitude ________?

direction __upward/downward?

Explanation / Answer

a) a = 40/14 - 9.81=-6.95

so 6.95 downward


2) F - friction = ma

a = 45/7=6.43


3) a) 45-2.5*9.81=20.475 upward


b) a = 20.475/2.5=8.19

upward