# Constant acceleration

1. Jun 19, 2012

### nbroyle1

A Cessna aircraft has a liftoff speed of 120 km/h.

(a) What minimum constant acceleration does the aircraft require if it is to be airborne after a takeoff run of 250 m?
(b) How long does it take the aircraft to become airborne?

I tried using an equation for constant acceleration and plugged in: .277^2=0+2a(250). When I solved for a I got .000153 and it was incorrect. any suggestions?

2. Jun 19, 2012

### collinsmark

Where did the "0.277" figure come from?

(Edit: And does 27.7 centimeters per second even sound like a reasonable velocity for the liftoff speed of a Cessna aircraft?)

3. Jun 19, 2012

### nbroyle1

After I converted the kilometers per hour to meters per second

4. Jun 19, 2012

### collinsmark

You might want to try that calculation again.

5. Jun 19, 2012

### nbroyle1

thats my problem it should be 44.44m/s

6. Jun 19, 2012

### nbroyle1

thanks

7. Jun 19, 2012

### collinsmark

Ummm, :uhh: Try that one more time.

8. Jun 19, 2012

### nbroyle1

i meant 33.33m/s haha

9. Jun 19, 2012

### collinsmark

That sounds better.

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