# Dynamics Question #4

1. May 16, 2008

### looi76

1. The problem statement, all variables and given/known data
An aeroplane of mass 20 tonne lands on an aircraft carrier with a horizontal velocity of $$80ms^{-1}$$. A $$100m$$ runway is available.
(a) What must be the acceleration to bring the aeroplane to rest safely?
(b) What retarding force is requires?

2. Relevant equations
$$v^2 = u^2 + 2as$$
$$F = m.a$$

3. The attempt at a solution
$$m = 90 \times 10^3kg \ , \ v = 80ms^{-1} \ , \s = 100m$$

(a) $$v^2 = u^2 + 2as$$
$$0^2 = 80^2 + 2 \times a \times 100$$
$$-80^2 = 200a$$
$$a = \frac{-80^2}{200}$$
$$a = -32ms^{-2}$$

(b) $$F = m.a$$
$$F = 90 \times 10^3 \times -32$$
$$F = -2.9 \times 10^6 N$$

Last edited: May 16, 2008
2. May 16, 2008

### alphysicist

Hi looi76,

I think your mass for the airplane is incorrect. Am I misunderstanding your numbers? How did you get 90000 kg?

3. May 17, 2008

### CFDFEAGURU

Check your conversion factors for tonne to kilograms.