Question

a marker is rolled horizontally off the top of a table. after 5 seconds the marker lands on the ground with a final velocity of -2.5 m/s. which kinematic equation would be most useful for finding the ball’s initial velocity? (assume a = -9.8 m/s^2)
a $vec{v}=vec{v}_{0}+vec{a}delta t$
b $delta x = (\frac{vec{v}+vec{v}_{0}}{2})delta t$
c $delta x=vec{v}_{0}delta t+\frac{1}{2}vec{a}(delta t)^{2}$
d $vec{v}^{2}=vec{v}_{0}^{2}+2vec{a}delta x$
e $delta x=vec{v}delta t-\frac{1}{2}a(delta t)^{2}$
(1 point)

Explanation:

Step1: Identify knowns and unknown

We know final velocity $\vec{v}$, time $\Delta t$ and acceleration $\vec{a}$, want $\vec{v}_0$.

Step2: Analyze kinematic equations

The equation $\vec{v}=\vec{v}_0+\vec{a}\Delta t$ directly relates final - velocity, initial - velocity, acceleration and time.

Answer:

A. $\vec{v}=\vec{v}_0+\vec{a}\Delta t$