A soccer ball is kicked straight upwards with an initial vertical speed of 8.0 meters per second. We can ignore air resistance. How long does it take the ball to have a downwards speed of 4.0 meters per second?
Question
Question
A soccer ball is kicked straight upwards with an initial vertical speed of 8.0 meters per second. We can ignore air resistance. How long does it take the ball to have a downwards speed of 4.0 meters per second?
Answer:
1.22 seconds
Explanation:
Given:
final velocity ‘vf’ = 8 m/s,
initial velocity ‘vi’ = -4 m/s (downward, therefore negative)
accalaration due to gravity ‘g’ = 9.8 m/s²
->As the ball undergoes a vertical motion. using the formula
g = (vf – vi ) / t
time ‘t’ = (vf – vi )/g
Substituting all the required values in above eq.
t = 8-(-4) /9.8 => (8+4)/9.8
t = 12/9.8
t = 1.22 sec
Therefore, it takes 1.22 sec for ball to have a downwards speed of 4.0 meters per second
Answer:
1.22 s
Explanation:
From the question, the ball undergoes a vertical motion.
Applying
g = (v-u)/t…………….. Equation 1
Where g = acceleration due to gravity, v = final velocity, u = initial velocity, t = time.
make t the subject of the equation
t = (v-u)/g………….. Equation 2
Let: The upward be taken as positive direction, and downward be taken as negative direction.
Given: v = 8 m/s, u = -4 m/s (downward) g = 9.8 m/s²
Substitute into equation 2
t = [8-(-4)]/9.8
t = (8+4)/9.8
t = 12/9.8
t = 1.22 s