Problema Solution

If a projectile is shot vertically into the air (from the ground) with an initial velocity of 150 feet per second, its distance y(in feet) above the ground t seconds after it is shot is given by y= 150t - 16t² (neglecting air resistance.)

A.) Find the times when y is zero, and interpret the results physically.

B.) Find the times when the projectile is 189 feet off the ground. (Compute answers to two decimal places.)

Answer provided by our tutors

A.) Find the times when y is zero, and interpret the results physically.


since y= 150t - 16t^2 we need to solve the quadratic equation


150t - 16t^2 = 0


by solving we find


t1 = 0 s


t2 = 9.275 s


click here to see the step by step solution of the equation


Click to see all the steps



the projectile is on the ground at the starting moment t2 = 0 seconds.


after t2 = 9.375 seconds the projectile will hit the ground.



B.) Find the times when the projectile is 189 feet off the ground. (Compute answers to two decimal places.)


since y= 150t - 16t^2 we need to solve the quadratic equation


150t - 16t^2 = 189


by solving we find


t1 = 1.5 s


t2 = 7.875 s or 7.88 s rounded to 2 decimal places


click here to see the step by step solution of the equation


Click to see all the steps



the projectile is 189 ft above the ground 1.5 second and 7.88 seconds after the what it is shot.