Question

A small object is given an initial downward velocity of 3 m/s.
a. What is its final velocity if it falls freely for 5 seconds?
b. What is its displacement from the initial position after 5 seconds?
c. How far did it travel during the 4th second of its fall?

Answer 1

given

initial velocity, vo = -3 m/s

a) vf = vo - g*t

= -3 - 9.8*5

= -52 m/s <<<<<<--------Answer

negative sign indicates downward.

b) displacement in 5 seconds,

delta_y = vo*t - (1/2)*g*t^2

= -3*5 - (1/2)*9.8*5^2

= -137.5 m

negative sign indicates downward.

c) displacement of the object in nth second,

delta_y = vo - (n-1/2)*g

= -3 - (4 - 1/2)*9.8

= -37.3 m

so, distance traveled in 4th second, d = 37.3 m <<<<<<<----------Answer

negative sign indicates downward.

Note: If you need only magnitude neglect the negative sign.
Please comment for any further clarification.