A tennis ball is thrown vertically upward with an initial velocity of 8 m/s.
What will the ball’s speed be when it returns to its starting point?
How long will the ball take to reach its starting point?
With an average acceleration of -1.2 m/S2, how long will it take a cyclist to bring a bicycle with an initial speed of 6.5 m/s to a complete stop?
A car traveling at 7.0 m/s accelerates uniformly at 2.5 m/s2 to reach a speed of 12.0 m/s. How long does it take for this acceleration to occur?
tennis ball.
on launch, v = 8
on return, v = -8
for the time, 8-9.8t = -8
now you try the others. Just use your basic equations of motion.
for example:
v = initial v + a t
x = initial x + initial v * t + (1/2) a t^2
To find out the ball's speed when it returns to its starting point, we can assume that the only force acting on the ball is gravity. We know that the initial velocity of the ball is 8 m/s and it is thrown vertically upward. As the ball reaches its peak height and starts falling back down, its speed will increase due to the acceleration by gravity.
To find the speed when it returns to its starting point, we can use the equation:
vf = vi + at
Where:
vf = final velocity
vi = initial velocity
a = acceleration
t = time
In this case, the ball is thrown vertically upward, so the final velocity when it returns to its starting point will be the negative of the initial velocity. Therefore, vf = -8 m/s.
The acceleration due to gravity is approximately 9.8 m/s², and since the ball is moving in the opposite direction of acceleration when it returns to its starting point, the value of acceleration will also be negative. So, a = -9.8 m/s².
Using these values, we can rearrange the equation:
vf = vi + at
-8 = 8 + (-9.8)t
Simplifying further:
-8 = 8 - 9.8t
-8 - 8 = -9.8t
-16 = -9.8t
Dividing both sides by -9.8:
-16 / -9.8 = t
t ≈ 1.63 seconds
Therefore, the ball will take approximately 1.63 seconds to reach its starting point.
To summarize:
- The ball's speed when it returns to its starting point will be 8 m/s.
- The ball will take approximately 1.63 seconds to reach its starting point.
A robot drops a camera off the rim of a 239 m height cliff on Mars, where the free- fall acceleration is -3.7 m/s2 .
Find the velocity with which the camera hits the ground.
Find the time required for it to hit the ground.