Question

Physics questions!

Answer 1

Please answer the orange questions which there is a question mark. Each question in a different page. So three medals.

Answer 2

Ok #36 please! I have my answer. I will send it in a sec!

Answer 3

I got this:

so I can write this:
\[\Large {m_1}{v_1} - {m_2}{v_2} = \left( {{m_1} + {m_2}} \right)v\]
from which I got:
v= +4 m/sec

Answer 4

How !?

Answer 5

using my reference system, we can write:
\[\Large \begin{gathered}
{{\mathbf{v}}_{\mathbf{1}}} = \left( {{v_1},0} \right) \hfill \\
{{\mathbf{v}}_{\mathbf{2}}} = \left( { - {v_2},0} \right) \hfill \\
\end{gathered} \]

Answer 6

Are you sure that is

m1v1 - m2v2 or m1v1 + m2v2?

Answer 7

no, since what is conserved is the vector which represents the total momentum, actually our equation is:
\[\Large {m_1}{{\mathbf{v}}_{\mathbf{1}}} + {m_2}{{\mathbf{v}}_{\mathbf{2}}} = \left( {{m_1} + {m_2}} \right){\mathbf{v}}\]

Answer 8

Exactly, it is a closed system. Energy is conserved.

Now lets plug in the numbers.

Answer 9

now we have to go from vectors to components, and as I wrote before, we can write:
\[\begin{gathered}
{{\mathbf{v}}_{\mathbf{1}}} = \left( {{v_1},0} \right) \hfill \\
{{\mathbf{v}}_{\mathbf{2}}} = \left( { - {v_2},0} \right) \hfill \\
\end{gathered} \]

Answer 10

what is v2? Motor or truck?

Answer 11

v_2 is the motor

Answer 12

furthermore:
\[\Large {v_1} = \left| {{{\mathbf{v}}_{\mathbf{1}}}} \right|,\quad {v_2} = \left| {{{\mathbf{v}}_{\mathbf{2}}}} \right|\]

Answer 13

Wait a moment.

Answer 14

In the question it says the truck is going west. West is the negative direction. Motorist is going opposite of west which is east! It is postive velocity. Truck should have -ve velocity.

Answer 15

ok! Then our correct drawing is:

and the previous equation will become:
\[\Large \begin{gathered}
- {m_1}{v_1} + {m_2}{v_2} = \left( {{m_1} + {m_2}} \right)v \hfill \\
{{\mathbf{v}}_{\mathbf{1}}} = \left( { - {v_1},0} \right) \hfill \\
{{\mathbf{v}}_{\mathbf{2}}} = \left( { + {v_2},0} \right) \hfill \\
\end{gathered} \]

Answer 16

and the answer is:
v= -4 m/sec

Answer 17

That means I was right? I got -4 m/s

Answer 18

yes!

Answer 19

Ok great, thank you!

I have to go, I will ask my other questions later.

Answer 20

ok!

Answer 21

Just wondering are you here in openstudy tomorrow. On Thursday I have a physics exam. I was wondering if I have few quick question, Is it ok I ask you?

Answer 22

yes! I will stay in OpenStudy tomorrow, and I can help you

Answer 23

At what time are you in openstudy, and when you leave?

Answer 24

I will be here in OpenStudy at 6:00 am (Italy Time zone)

Answer 25

Ok I will manage mt time. Thank you, you are a very supportive tutor.

Answer 26

:)