A 25,000 kg traveling east collides with a 2,000 kg truck standing still on the tracks. After the collision the train and truck are moving together at 22.3 m/s. How fast was the train going to begin with? Assume there is no friction. My frame of reference sets east a positive​

Respuesta :

Answer:

24.084 m/s

Explanation:

From the law of conservation of linear momentum

Total momentum before collision equals to the total momentum after collision

Since momentum=mv where m is mass and v is velocity

[tex]M_{truck}V_{truck}=V_{common}*(M_{truck} +M_{standing})[/tex] where [tex]M_{truck}[/tex] is the mass of the truck, [tex]V_{truck}[/tex] is velocity of the truck, [tex]V_{common}[/tex] is the common velocity of moving and standing truck after collision and [tex]M_{standing}[/tex] is the mass of the standing truck

Making [tex]V_{truck}[/tex] the subject we obtain

[tex]V_{truck}=\frac { V_{common}*(M_{truck} +M_{standing})}{M_{truck}}[/tex]

Substituting [tex]M_{truck}[/tex] as 25000 Kg, [tex]V_{common}[/tex] as 22.3 m/s, [tex]M_{standing}[/tex] as 2000 Kg we obtain

[tex]V_{truck}=\frac { 22.3 m/s *(25000 Kg +2000 Kg)}{25000}= 24.084 m/s[/tex]

Therefore, assuming no friction and considering that after collision they still move eastwards hence common velocity and initial truck velocities are positive

The truck was moving at 24.084 m/s