Question

A ball is thrown directly up in the air from a height of 5 feet with an initial velocity of 60 ft/s. Ignoring air resistance, how long until the ball hits the ground? Use the formula 2003-19-06-00-00_files/i0080000.jpg, where h is the height of the ball in feet and t is the time in seconds since it is thrown. Round your answer to the nearest tenth. A. 2.1 seconds B. 3.8 seconds C. 2.4 seconds D. 1.8 seconds

Answer 1

Answer:

Time, t = 3.8 seconds

Explanation:

It is given that,

A ball thrown up in air from a height of 5 feet.

Initial velocity, v₀ = 60 ft/s

When an object is thrown with initial velocity of v then the equation of motion is given by :

$h(t)=-16t^2+v_ot+s_o$  

s₀ = height at t = 0, s₀ = 5 ft

$-16t^2+60t+5=0$  

Solving above quadratic equation, we get :

t = 3.8 seconds.

Hence, the correct option is (B) " 3.8 seconds ".              

Answer 2

I think it would be D because it would make more sense.