- #1

scytherz

- 11

- 0

## Homework Statement

A physics professor bicycles through air at a speed of v= 36 km/hr. The density of Air is 1.29 kg per m^3. the professor has a cross section of 0.5 m^2. assume all of the air the professor swept out is accelerated to v.

a.) What is the mass of the air swept out by the professor in one second? (ans. 6.45 kg)

b.) What is the power to required to accelerate this air? (323 w)

## Homework Equations

p=w/t

P= Fv

## The Attempt at a Solution

Multiplying the cross section to the velocity 10 m/s(36km/hr) divided by 1 sec , i got 5 m^3.. and then multiplying it to the denisty, i got 6.45 kg.. the correct ans was 6.45 kg... but somehow i got a feeling my solution is flawed... is my solution is correct and also i can't find the correct answer in letter b.. I tried substituting P= Fd/t or P=ma/t and gor 64.5 W, which is wrong... can someone tell me where did i go wrong in finding the power required to accelerate in air...?