7. A ball is pushed off a cliff and reaches a velocity of 18 m/s downward after 6.4 seconds.

What was its acceleration during this time frame? (Its initial velocity is 0)



Answer :

To determine the acceleration of the ball as it is pushed off the cliff, we can use one of the fundamental equations of motion. The equation that relates acceleration ([tex]\( a \)[/tex]), initial velocity ([tex]\( v_i \)[/tex]), final velocity ([tex]\( v_f \)[/tex]), and time ([tex]\( t \)[/tex]) is:

[tex]\[ a = \frac{v_f - v_i}{t} \][/tex]

Let's break this down step-by-step:

1. Identify known values:
- Initial velocity ([tex]\( v_i \)[/tex]): The ball starts from rest, so [tex]\( v_i = 0 \, \text{m/s} \)[/tex].
- Final velocity ([tex]\( v_f \)[/tex]): The ball reaches [tex]\( 18 \, \text{m/s} \)[/tex] downward.
- Time ([tex]\( t \)[/tex]): The time taken to reach this velocity is [tex]\( 6.4 \)[/tex] seconds.

2. Substitute the known values into the equation:
[tex]\[ a = \frac{18 \, \text{m/s} - 0 \, \text{m/s}}{6.4 \, \text{s}} \][/tex]

3. Perform the calculation:
[tex]\[ a = \frac{18 \, \text{m/s}}{6.4 \, \text{s}} \][/tex]

4. Simplify the fraction:
[tex]\[ a = 2.8125 \, \text{m/s}^2 \][/tex]

Hence, the acceleration of the ball during this time frame is [tex]\( 2.8125 \, \text{m/s}^2 \)[/tex].