Question

A ball is thrown horizontally from a 20-m-high building with a speed of 5.0m/s

a. Draw a graph of Vx, the vetical velocity, as a function of time.
b. Draw a graph of Vy, the vertical velocity, as a function of time.

Answer 1

1) Horizontal velocity, Vx

Vx is constant and equal to 5.0 m/s

The graph Vx(t) = 5.0 m/s is a horizontal line (parallel to the horizontal t-axis). that intercepts the vertical-axis at 5.0 and runs from t = 0 to t = 2.

2) Vertical velocity, Vy

Vy = gt = 10t

d = at^2 / 2 => tmax = √(2d / a) = √(2*20m/10m/s^2) = 2 s

Graph Vy is an inclined line with slope 10 m/s^2, that runs from t =0 to t = 2 s, and passes through the points (0,0), (1,10), and (2,20).