The big deal with 2-dimensional kinematics is that we can break
most problems back down into one dimensional problems if the
acceleration is constant.
For example, vx =
vx0 +
axt where
vx0 is the x component of the velocity
at time t=0s, vx is the x component of
the velocity at time t, and ax is the
x component of the acceleration.
In the vertical direction, the same formula is valid for all of the
y components: vy =
vy0 +
ayt where
vy0 is the y component of the velocity
at time t=0s, vy is the y component of
the velocity at time t, and ay is the
y component of the acceleration.
In projectile motion gravity is the only force acting on the ball.
We will always choose the y-axis to be exactly vertical and in this
case positive in the upward direction. Since gravity acts straight
down, the x component of the acceleration will be 0 m/s2
and the y component of the acceleration will be -9.80
m/s2.
Consider the following case: you kick a ball. Just after it leaves
your foot the x component of the velocity of the ball is 17.7 m/s
and the y component of the velocity of the ball is 31.5 m/s.
After a time t=1.80 s, what is the x component of velocity of the
ball?
Tries 0/10 |
After a time t=1.80 s, what is the y component of the velocity of the ball?
a) Along the horizontal direction we have
vx = vx0 + ax t
Vx0 = 17.7 m/s
ax =0
=> Vx = 17.7 m/s
Along y direction
vy = vy0 + ay t
Vy0 = 31.5 m/s
ay = -9.8 m/ss
Vy = 31.5 - (9.8) (1.8)
=> Vy = 13.86 m/s
The big deal with 2-dimensional kinematics is that we can break most problems back down into...
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