7. Katie and her best friend Liam play tennis every Saturday morning. When Katie serves the ball to Liam, it
1 answer:
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
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Answer:
23376 days
Explanation:
The problem can be solved using Kepler's third law of planetary motion which states that the square of the period T of a planet round the sun is directly proportional to the cube of its mean distance R from the sun.
where k is a constant.
From equation (1) we can deduce that the ratio of the square of the period of a planet to the cube of its mean distance from the sun is a constant.
Let the orbital period of the earth be and its mean distance of from the sun be
.
Also let the orbital period of the planet be and its mean distance from the sun be
.
Equation (2) therefore implies the following;
We make the period of the planet the subject of formula as follows;
But recall that from the problem stated, the mean distance of the planet from the sun is 16 times that of the earth, so therefore
Substituting equation (5) into (4), we obtain the following;
cancels out and we are left with the following;
Recall that the orbital period of the earth is about 365.25 days, hence;