Answer:
Initial velocity = 39.2m/s
Maximum height is 78.4m
Explanation:
Given
[tex]Time, t = 4s[/tex]
Solving (a): Initial Velocity
Using first law of motion:
[tex]v = u + at[/tex]
Where
[tex]v = final\ velocity = 0[/tex]
[tex]u = iniital\ velocity = ??[/tex]
[tex]a = acceleration = -g[/tex] [g represents acceleration due to gravity]
[tex]t = 4[/tex]
Substitute these value in the above formula:
[tex]v = u + at[/tex]
[tex]0 = u - g * 4[/tex]
[tex]0 = u - 9.8 * 4[/tex]
Take g as 9.8m/s²
[tex]0 = u - 39.2[/tex]
[tex]u = 39.2m/s\\[/tex]
Hence, initial velocity = 39.2m/s
Solving (b): Maximum Height
This will be solved using second equation of motion
[tex]s = ut + \frac{1}{2}at^2[/tex]
This becomes
[tex]s = ut - \frac{1}{2}gt^2[/tex]
Substitute values for u, t and g
[tex]s = 39.2 * 4 - \frac{1}{2} * 9.8 * 4^2[/tex]
[tex]s = 156.8 - 78.4[/tex]
[tex]s = 78.4[/tex]
Hence, the maximum height is 78.4m
