## A series of questions from Edinburgh University's Physics Skills papers

**Road Safety**

A chicken is waiting
to cross a 5m, one way road, along which cars are travelling

at 40m/s. If the chicken can accelerate at 5m/s2
to a maximum speed of

5m/s, how big a gap in
the traffic does she require in order to cross the road

without a car passing
her during the crossing.

**Death wish**

Depressed by its
inability to solve physics problems, a chicken decides in end it

all in the traditional way. A bus will
pass at precisely 12 oÕclock, on a road parallel

to the field edge, which is 100m from
the coop at the closest point. The
bus

travels at 10m/s, and
the chicken can run at 5m/s. What
is the latest time that

the chicken can exit
the coop?

Why don't penguin's
feet freeze?

**Some Chickens are
cooler than others**

A large frozen
chicken at -10 C is dropped into a pot containing an equal mass

of brine at
0C. After some time, the chicken has not thawed. What temperature

is the chicken,
and what fraction of the chicken melts.

[Assume the brine
has a freezing point of -15C and heat capacity of 3.2kJ/kg/K,

independent of
concentration. Treat the chicken
as water ice with heat capacity

2kJ/kg/K, latent
heat of melting 334kJ/kg]

Though not for long

**Unscheduled
Pantechnion Incident**

A farmer wishes to
measure the width of a road. He
releases a flock of 100

chickens
simultaneously from one side of the road.
These chickens are known

to cross roads
directly at an average speed of 1m/s and standard deviation of

0.2m/s. after 5 seconds the experiment is abruptly
ended by the sudden arrival

of a large lorry,
at which point only 17 chickens have crossed the road.

Estimate the width
of the road, and the error on your estimate.

**Ruffled Feathers**

A coop is demolished
to make way for a 5MW wind turbine.
One of the chickens flies

into space where it is
annihilated in an unfortunate encounter with an antimatter

antichicken. How long does the wind turbine have to operate
to generate the equivalent

amount of energy?

Bottom of Form

**In a flap**

A closed 1 tonne lorry
is carrying 500kg of chickens to market.
It has to cross a bridge

which can bear a
maximum weight of 1.2tonnes. The
driver attempts to lighten the load

by getting the
chickens to fly up. Will this
help?

**Getting over it.**

50 chickens are
walking across a 10m wide icy road at 2m/s. Being cautious birds, they leave enough gap

between one another to stop at a deceleration rate of 1m/s^2.
How long does it take them all to cross?

On their return, enthused by the
prospect of a feed, they decide to run across, at
5m/s again leaving

enough space to stop. Now how long does it
take them?

**McChicken**

A spacechicken finds itself on the moon.
How many chicken sandwiches contain enough energy to put it
into orbit?

[ A typical chicken sandwich has 385 nutritional calories. One nutritional calorie
is equivalent to an energy of 4.2 kJ. The radius and mass of the moon are 1738
km and 7.34 x 10^{22} kg respectively.]