Answer all of these questions and you will get the brain list answer
2 answers:
Answer:
a). whenever the ball is at it's highest on either side (it stops, so kinetic energy is 0)
b). whenever the ball is at the bottom (A) - it cannot go lower, so potential energy is 0.
c). whenever the ball accelerates, so when it's going down from either side before reaching A (at that point it's going up and thus slowing down).
d). whenever the ball is ascending, so when it's goind up from A to either side
Explanation:
Kinetic energy is based on velocity
mass is constant, so we need to find a point where v = 0 to solve a), and points where v is increasing to solve b).
Potential energy is based on height vs "the bottom" (here, the minimum altitude is "the bottom").
mass and gravitational acceleration are constant, so we need to find a point where h = 0 to solve b) and the points where h is increasing to solve d).
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a. 4.52 m/s south
Velocity is a vector, whose magnitude is defined as the ratio between the displacement of the object and the time taken for the displacement to occur:
where
d is the displacement
t is the time
Velocity is a vector, so it also has a direction, which corresponds to that of the displacement.
For the ball in this problem,
d = 9.5 m south
t = 2.1 s
Substituting, we find:
and the directiion is the same as the displacement (south).
b. 4.52 m/s north
For this part, we must keep in mind that the speed is the magnitude of the velocity; however, speed is a scalar, so it does not have a direction.
Here we are told that the tennis ball travels at constant speed, so on its way back from Liam to Katie the ball's velocity is still the same as before, therefore
However, this time the direction is opposite to before, since the ball is travelling in the opposite direction.
Therefore, the ball's velocity when Liam returns Katie's service is
4.52 m/s north