A ball is thrown straight down and takes 1.10 s to travel (fall) a distance of 9

Question

A ball is thrown straight down and takes 1.10 s to travel (fall) a distance of 9.2 m.
1a.)Calculate the initial velocity of the ball. Your answer should have 3 significant figures.

1b.)Calculate the velocity of the ball at t = 0.900 s. Your answer should have 3 significant figures.

2.)A rock is tossed straight up with a speed of 24 m/s. When it returns, it falls into a hole 12 m deep. In other words, assume that the rock lands 12 m lower than the height from which it was thrown. Take "up" to be the positive direction for this problem. Although the numbers in this problem have less than 3 significant figures, please enter your answers with at least 3 significant figures, and remember that velocity is a vector.

2a) What is the rock's velocity as it hits the bottom of the hole?
m/s

2b) How long is the rock in the air, from the instant it is released until it hits the bottom of the hole?
s

Explanation / Answer

1)

1a) Use equation,

h=vi*t+1/2*a*t^2=

-9.2=Vi*1.1+1/2*-9.8*1.1^2           => Vi=-2.97m/s

1b)Use equation,

Vf=Vi+a*t

Vf= -2.97-9.8*0.9= -11.8m/s

2)

2a) Use equation,

Vf^2=Vi^2+2*a*h

Vf^2= 24^2+2*-9.8*-12           => Vf= -28.5m/s

2b)Use equation

h=Vi*t+1/2*a*t^2

-12=24*t+1/2*-9.8*t^2                =>   t= 5.35s

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