A football is kicked with an initial velocity v=9i+12j. Find the speed in (m/s) of the ball after 2.4s
A) 9.2 B) 10.8 C) 12 D) 15
To find the speed of the ball after 2.4 seconds, we can use the equation of motion:
v = u + at
where:
v = final velocity (speed)
u = initial velocity
a = acceleration
t = time
In this case, the initial velocity is given as v = 9i + 12j m/s, and we need to find the final velocity after 2.4 seconds. Since the acceleration is not given, we'll assume it's zero as there is no force acting on the ball once it's kicked.
Using the equation, we have:
v = u + at
Since there is no acceleration, we can simplify the equation to:
v = u
So, the final velocity after 2.4 seconds is equal to the initial velocity.
Thus, the speed of the ball after 2.4 seconds is equal to the magnitude of the initial velocity:
|v| = sqrt((9)^2 + (12)^2)
|v| = sqrt(81 + 144)
|v| = sqrt(225)
|v| = 15 m/s
Therefore, the correct answer is D) 15.
Yf = Yo + g*t = 12 - 10*2.4 = -12 m/s.
Vf = sqrt(9^2 + 12^2) = 15 m/s.