Question

A projectile is launched in the air with an initial velocity of 40 m/sec from a height of 1.2 meters. Which of the following equations represents the projectiles height,h, in meters, over time, t, in seconds?
A.h=-40t^2+1.2
B.h=-16t^2+40t+1.2
C.h= -4.9t^2+1.2
D.h= -4.9t^2+40t+1.2

Answer 1

For this case, the first thing that should be taken into account is the following kinematics equation in its generic form:
 h = a * (1/2) * t ^ 2 + vo * t + h0
 Where,
 a: acceleration
 vo: initial speed
 h0: initial height.
 t : time
 h: final height
 Substituting the values:
 h = -4.9 t ^ 2 + 40t + 1.2
 Note:
 g = 9.8 m / s
 Answer:
 D  h = -4.9 t ^ 2 + 40t + 1.2