# Determine the angular velocity in rad/s and degrees/s

i think i have part a right (but who knows). i dunno about part b. any help is appreciated!

## Homework Statement

1) a car is travelling at 80km/h, and is towing a trailer. the wheels of the trailer are 40cm in diameter.

a) determine the angular velocity in rad/s and degrees/s

radius = 40cm/2 = 20 cm
distance travelled in 1 hr = 80km = 8,000,000
1 hr = 3600s

distance travelled in 1s = 8,000,000/3600 = 2,222.222

#of rotation in 1s = 2222.222/20pi = 35.37

angular velocity = 35.27 x 2pi = 70.74pi rads

70.74pr x (180/pi) = 6,372 degrees per second

b) through what angle does the tire turn in 60s? state your answer in radians and degrees

for this one i could just go 35.37 x 60s = 2122.7
360degrees x .7 = 252degrees?

?

and then i have to explain why radians are better than degrees in these types of questions. i havent the foggiest idea.

~Amy

## The Attempt at a Solution

Integral
Staff Emeritus
Gold Member
Circumfrence is $\pi$ d, not $\pi$ r

thanks

so:

a) determine the angular velocity in rad/s and degrees/s

radius = 40cm/2 = 20 cm
distance travelled in 1 hr = 80km = 8,000,000
1 hr = 3600s

distance travelled in 1s = 8,000,000/3600 = 2,222.222

#of rotation in 1s = 2222.222/40pi = 17.7

angular velocity = 17.7 x 2pi = 35.4pi rads

35.4pi x (180/pi) = 6,372 degrees per second

b) through what angle does the tire turn in 60s? state your answer in radians and degrees

17.68 x 60s = 1060.8
360degrees x .8 = 288degrees?