# Carousel physics. Calculating constant speed and distance.

## Homework Statement

A child a rides a carousel at t = 0 and moves in a circle that is 8 m in circumference at a speed of constant modulus of 1m / s. determine:
a) the movement of t = 0s to t = 1s
b) the average speed from t = 0s to t = 3s
c) the average acceleration between 1s and 3s

## Homework Equations

I've got these that i figure work:
v= vxi + vyj
and
movement = Δxi + Δyj

## The Attempt at a Solution

Given that the correct answers(provided by my textbook) should be
a) (0,900i -0,372j)m
b) (0,300i - 0,724j)m/s
c) (-0,707i) m/s2

I dont seem to know how to apply the equations above to land these answers... Vectors confuse me. For instance, Δx and Δy represent what ? I'm stuck. HELP!

## Answers and Replies

Andrew Mason
Science Advisor
Homework Helper
a) is a vector subtraction problem. Draw the displacement from the centre at t=0 and the displacement at t=1 sec. What is the difference? (ie the displacement at t=0 minus the displacement at t=1)?

b) Use the method in a) to find the change in displacement from t=0 to t=3 sec. How would you define the average speed in terms of this displacement and the time difference?

c) What is the change in velocity between t=1 sec. and t=3 sec? (Hint: Draw the velocity vectors at each point and subtract the velocity at t=3 from that at t=1). How would you define the average acceleration in terms of this change in velocity and the time difference?

AM

So ive got the a and the b down but as for c, i dont know what you mean

Andrew Mason
Science Advisor
Homework Helper
So ive got the a and the b down but as for c, i dont know what you mean
How do you define the average acceleration?

Hint: It involves a change in the velocity (a vector). How would you determine the change in velocity between t=1 and t=3?

AM

How do you define the average acceleration?

Hint: It involves a change in the velocity (a vector). How would you determine the change in velocity between t=1 and t=3?

AM

Oh wow. I put down the wrong number over and over again. But I got it. ITs -0,707i.