4.2 Excercise 3

h <- 1 
dVdt <- 5 

1cm

r <- 1
cat(dVdt/(2* pi* r), "cm/s")
## 0.7957747 cm/s

10cm

r <- 10
cat(dVdt/(2* pi* r), "cm/s")
## 0.07957747 cm/s

100cm

r <- 100
cat(dVdt/(2* pi* r), "cm/s")
## 0.007957747 cm/s