Question

Tina is looking out a window and throws marble straight downward toward the sidewalk below at a speed of 5.00 m/s and the window is 39.0 meters above the sidewalk. Answer the two questions below, using three significant digits. Part A: What is the speed of the ball (11) when it hits the ground? Number m/s (Remember: enter a magnitude.) Part B: After 1.90 s, how far down has the marble travelled?

Answer 1

Answer:

a) 28.1 m/s

b) 27.2 m

Explanation:

a)

Consider the motion of the marble in downward direction taking down direction as positive

v₀ = initial velocity = 5 m/s

v = final velocity as it hits the ground = ?

a = acceleration = 9.8 m/s²

d = vertical height traveled = 39 m

Using the equation

v² = v₀² + 2 a d

v² = 5² + 2 (9.8) (39)

v = 28.1 m/s

b)

t = time of travel = 1.90 s

y = vertical distance traveled

Using the equation

y = v₀ t + (0.5) a t²

y = (5)(1.90) + (0.5) (9.8) (1.90)²

y = 27.2 m