Answer:
W = - 3431250 [N]
Explanation:
In order to solve this problem, we must use the theorem of work and energy conservation. This theorem tells us that the initial mechanical energy of a body plus the work done on this body must be equal to the final mechanical energy of the body. We must remember that the mechanical energy of a body is equal to the sum of kinetic energies plus potential energy plus elastic energy.
In this problem, we only have kinetic energy.
[tex]E_{1}+W_{1-2}=E_{2}\\where:\\E_{1}=E_{pot}+E_{kine}+E_{elas}\\E_{pot} = 0\\E_{elas}=0\\E_{kine}=\frac{1}{2} *m*v^{2}[/tex]
And we have:
m = mass = 1220 [kg]
v = velocity = 75 [m/s]
As the carriage stops the final kinetic energy is zero.
Now replacing:
[tex]\frac{1}{2} *1220*(75)^{2} +W_{1-2}=0\\W_{1-2}= - 3431250[N][/tex]
Note: The negative force means that the force has to be carried out by the carriage. That is, no external force acts on the car to stop it.
