If a projectile is fired straight up at a speed of 10 m/s,the total time to return to its starting position is about
A)1 second.
B)2 seconds.
C)10 seconds.
D)20 seconds.
E)not enough information to estimate

Question

Quizplus · Accepted Answer

When the projectile is fired straight up, it will continue to rise until it reaches its maximum height and then begin to fall back down. At the maximum height, its velocity will be zero. Using the equation for displacement, we can determine the total distance traveled by the projectile:

d = (1/2)at^2 + v0t

Where a is the acceleration due to gravity (-9.8 m/s^2), v0 is the initial velocity (10 m/s), and t is the time it takes to reach maximum height and return to its initial position. Since the initial velocity is positive and the final velocity is also positive upon return to its initial position, we can simplify the equation to:

d = 2(1/2)at^2

d = -4.9t^2

Setting d = 0 (since it returns to its initial position), we can solve for t:

0 = -4.9t^2

t = sqrt(0) = 0

t represents the time it takes for the projectile to travel up and down, so we need to multiply by 2 to get the total time:

2t = 2(0) = 0

Therefore, the total time for the projectile to return to its starting position is approximately 2 seconds.

If a Projectile Is Fired Straight Up at a Speed