Fig. 2.1 shows a train Fig. 2.1
The total mass of the train and its passengers is 750000kg. The train is travelling at a speed of 84m/s.
The driver applies the brakes and the train takes 80s to slow down to a speed of 42m/s.
(a) Calculate the impulse applied to the train as it slows down,
impulse =
[3]
(b) Calculate the average resultant force applied to the train as it slows down,
force =
(2)

Explanation:

The impulse-momentum theorem states the impulse on an object is equal to the change in momentum of that object. Momentum is given by . Since mass is constant, the train's change in momentum is:

(two significant figures).

Impulse is also given as , where is the average force applied and is change in time. Since is given as , we have the following equation:

(two significant figures).

this means that the temperature of both substances will be equal