Wilma i. ball walks at a constant speed of 5.93 m/s along a straight line from point a to point b and then back from b to a at a constant speed of 3.15 m/s.
(a) what is wilma's average speed over the entire trip?
(b) what is wilma's average velocity over the entire trip?

a) The average speed is 4.11 m/s

b) The average velocity is zero.

Explanation:

Hi there!

a) The average speed is calculated as the traveled distance over the time taken to cover that distance:

a.s = d/t

Where:

a.s = average speed.

d = traveled distance.

t = time.

From A to B Wilma travels at a constant speed of 5.93 m/s. So, we can write the equation of average speed as follows:

5.93 m/s = d / t1

Where t1 is the time taken to travel the distance from A to B (d)

From B to A Wilma travels at 3.15 m/s, so the equation of average speed could be written as follows:

3.15 m/s = d / t2

Where t2 is the time taken to travel from B to A (d)

If we solve both equations for the time, we can get the total time of the trip by adding the expressions we obtain:

t1 = d / 5.93 m/s

t2 = d / 3.15 m/s

The total time of the trip is the sum of both times:

t1 + t2 = d / 5.93 m/s + d / 3.15 m/s

t1 + t2 = (3.15 m/s d + 5.93 m/s d) / (3.15 m/s)(5.93 m/s)

t1 + t2 = 9.08 m/s d / (3.15 m/s)(5.93 m/s)

The total traveled distance is 2 d and the total time is t1 + t2, so the average speed for the entire trip will be:

a.s = 2 · d / (t1 + t2)

a.s = 2 · d · ((3.15 m/s)(5.93 m/s) / 9.08 m/s d)

a.s = 4.11 m/s

The average speed is 4.11 m/s

b) The average velocity is calculated as the displacement over the elapsed time. The displacement is calculated as follows:

displacement = initial position - final position

In this case:

initial position = final position ( because Wilma returns to the starting point, there was no net displacement).

Then:

a.v = D/t

Where:

a.v = average velocity.

D = displacement

t = time.

a.v = 0/ t

a.v = 0

The average velocity is zero.

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.

answer: 2×10^-2kg

explanation: density= mass per volume

vol=mass/density

converting to s.i units we have;

3÷1000kg = 0.003

1.5÷100m = 0.15

0.003/0.15 = 0.02kg