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Science-Related Homework Help Physics Topic started by: s.h_math on Nov 25, 2021



Title: Collision questionnaire
Post by: s.h_math on Nov 25, 2021
A 50.0g bullet strikes a 7.00 kg wooden block. If the bullet becomes imbedded in the block and they both move off at a velocity of 5.00 m/s, what was the initial speed of the bullet?

Hi, I'm having trouble with on how to solve this problem here, they want the initial speed but I'm not sure how to do it.


Title: Re: Collision questionnaire
Post by: duddy on Nov 25, 2021
First, change 50.0 g to kg. It is 0.050 kg.

We don't know its velocity, so let's call it \(v_b\).

The stationary wooden block is 7.00 kg. Because it is stationary, it has a speed of 0 m/s.

This is an inelastic collision because the bullet gets embedded in the block. In addition, together they make a combined mass of 7.05 kg. The velocity is given to us as 5.00 m/s.

Use the same formula as we used in the previous question.

m*\(v_b\) + m*v = m*v

0.050*\(v_b\) + 7.0 kg*(0) = 7.5 kg*(5.00 m/s)

0.050*\(v_b\) = 7.5 kg * (5.00 m/s)

Solve for \(v_b\):

\(v_b\) = (7.05 kg * 5.00 m/s) / 0.050 kg

\(v_b\) = 705 m/s

You may watch this video for reference:

https://www.youtube.com/watch?v=nLf1DtUAieU