# Answer to Question #26381 in Mechanics | Relativity for abdullah

Question #26381

a baseball is hit so that it travels straight upward after being struck by the bat. a fan observes that it takes 3.00 seconds to reach it's maximum height. find (A) the ball initial velocity and (B) the height it reaches.

Expert's answer

a baseball is hit so that it travels straight upward after beingstruck by the bat. a fan observes that it takes 3.00 seconds to reach it's

maximum height. find

(A) the ball initialvelocity

The ball falls freelly,therefore:

v = v0 - g*t

v0 - the ball initialvelocity

g - gravitationalacceleration

t - time

When v = 0, t = 3.00sec:

0 = v0 - g*t => v0 = g*t

v0 = 9.8*3m/s= 29.4 m/s

Answer: v0 = 29.4 m/s

(B) the height itreaches.

The law conservation ofenergy:

m*g*h + 0= m*v0^2/2 + 0

h - maximum height

h = v0^2/(2g) = | v0 = g*t | = gt^2/2 = 44.1 m

Answer: h = 44.1 m

maximum height. find

(A) the ball initialvelocity

The ball falls freelly,therefore:

v = v0 - g*t

v0 - the ball initialvelocity

g - gravitationalacceleration

t - time

When v = 0, t = 3.00sec:

0 = v0 - g*t => v0 = g*t

v0 = 9.8*3m/s= 29.4 m/s

Answer: v0 = 29.4 m/s

(B) the height itreaches.

The law conservation ofenergy:

m*g*h + 0= m*v0^2/2 + 0

h - maximum height

h = v0^2/(2g) = | v0 = g*t | = gt^2/2 = 44.1 m

Answer: h = 44.1 m

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