Acar with mass m=1.43e3 kg is initially traveling directly east with a speed =25.0 m/s. it crashes into the rear end of a truck with mass =9000 kg moving in the same direction with speed =20.0 m/s. immediately after the collision the car has a speed =18.0 m/s in its original direction (the two do not stick together in this case). (a) what is the speed of the truck immediately after the collision?

  :  Speed of the truck immediately after the collision , to the east.

Explanation:

Theory of collisions

Linear momentum is a vector magnitude (same direction and direction as velocity) and its magnitude is calculated like this:

P=m*v

where

P:Linear momentum

m: mass

v:velocity

There are 3 cases of collisions : elastic, inelastic and plastic.

For the three cases the total linear momentum quantity is conserved:

P₀=Pf   Formula (1)

P₀ :Initial  linear momentum quantity

Pf : nitial  linear momentum quantity

Nomenclature and data

mc: car mass= 1.43*10³ kg  = 1430kg

V₀c: initial car speed,  = 25.0 m/s

Vfc: final car speed = 18.0 m/s

mt: truck mass =  9000 kg  

V₀t: initial truck speed, = 20.0 m/s

Vft: final truck speed

Problem development

For this problem the collision is inelastic because after the collision the objects are deformed .

Because the known speeds go east they are positive, we assume that the truck continues moving east after the collision and its speed will also be positive:

We apply formula (1)

P₀=Pf

mc*V₀c+mt*V₀t=mc*Vfc+mt*Vft

1430*25+9000*20=1430*18+9000*Vft

215750=25740+9000*Vft

Because the response was positive the truck moves east after the collision

answer: the metamorphic rocks are formed when they are exposed to high pressure and high temperatures. this happens when one of the earth's plates comes in contact with the other plate by traveling in opposite directions, straight into each other or slipping under one another. the friction that is caused by this activity results in   melting of rocks and when it cools they are known as metamorphic rocks. this process needs a controlled amount of pressure and temperature otherwise it may turn into magma.