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# Collision questionnaire

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A week ago
 Collision questionnaire 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. Read 41 times 1 Reply

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Staff Member
A week ago
 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*v0.050*$$v_b$$ + 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/sYou may watch this video for reference:
 - Master of Science in Biology- Bachelor of Science (Biology)- Bachelor of Education