How do u calc the unknown velocity in the following collisons between 2 trolleys ?

Question

before collision

trolley A goes 1.2ms/1 to the right it weighs 2kg

trolley B is at rest and weighs 1kg

after collision

both have velocity vectors to the right

any help will be appreciated

please explain your answer

the answer is +8ms/1

Answer 1

The general equation is: (m1)(v1)+(m2)(v2)=(m1+m2)(v)

m1=2 kg

v1=1.2 m/s

m2=1 kg

v2= 0 m/s (at rest)

(m1)(v1) = (2 kg)(1.2 m/s) = 2.4 kg*m/s

(m2)(v2) = (1 kg)(0 m/s) = 0 kg*m/s

We now have: 2.4 kg*m/s = (m1+m2)(v)

(m1+m2) = 3 kg

We now have: 2.4 kg*m/s = (3 kg)(v)

The variable is the final velocity.

Divide both sides by 3 kgs to isolate the variable.

2.4 kg*m/s divided by 3 kg cancels out the kgs and leaves us with m/s. 2.4/3 equals 0.8 m/s. The velocity is 0.8 m/s.