Y1, C5- Volumes of Revolution

Question 1

What is the equation for volume revolved around the y-axis

Answer 1

V = pi int(x^2)dy

Question 2

When integrating, what must the limits match

Answer 2

The ‘d’ part at the end e.g. t limits for dt, x limits for dx

Question 3

What is the formula for the volume of a curve revolved θ radians around the x axis

Answer 3

(θ/2) * int(y^2) dx

Question 4

What is the formula for the volume of a curve revolved θ degrees around the x axis

Answer 4

(pi/360) * θ * int(y^2) dx

Question 5

What is the formula for the volume of a cone

Answer 5

V = 1/3 * pi * r^2 * h

Question 6

What is the formula for the volume of a cylinder

Answer 6

V = pi * r^2 * h

Question 7

What are some limitations of models for volumes of revolutions

Answer 7

Measurements may not be accurate
Equation of curve may not fit accurately
Inside surface may not be smooth

Question 8

How do you structure an answer to: ‘The correct answer is … , evaluate your model’

Answer 8

State whether model is good or bad
Give a reason (11% off / correct to 3 s.f. etc)