Answer:
Explanation:
KE_s: Kinetic Energy Son
KE_f: Kinetic Energy Father.
Relationship
KE_f: = (1/4) KE_s
m_s: = (1/3) m_f
v_f: = velocity of father
v_s: = velocity of the son
Relationship
1/2 mf (v_f + 1.2)^2 = 1/2 m_s (v_s)^2 Multiply both sides by 2.
mf (v_f + 1.2)^2 = m_s * (v_s)^2 Substitute for the mass of the m_s
mf (v_f + 1.2)^2 = (m_f/3) * (v_s)^2 Divide both sides by father's mass
(v_f + 1.2)^2 = 1/3 * (v_s)^2 multiply both sides by 3
3*(v_f + 1.2)^2 = (v_s) ^2 Take the square root both sides
√3 * (v_f + 1.2) = v_s
Note
- You should work your way through all the cancellations to find the last equation shown about
- We have another step to go. We have to use the first relationship to get the final answer.
KE_f = (1/4) KE_s Multiply by 4
4* KE_f = KE_s Substitute (again)
4*(1/2) m_f (v_f + 1.2)^2 = 1/2* (1/3)m_f *v_s^2 Divide by m_f
2* (v_f + 1.2)^2 = 1/6 * (v_s)^2 multiply by 6
12*(vf + 1.2)^2 = (v_s)^2 Take the square root
2*√(3* (v_f + 1.2)^2) = √(v_s^2)
2*√3 * (vf + 1.2) = v_s
Use the second relationship to substitute for v_s so you can solve for v_f
2*√3 * ( v_f + 1.2) = √3 * (v_f + 1.2) Divide by sqrt(3)
2(v_f + 1.2) = vf + 1.2
Edit
2vf + 2.4 = vf + 1.2
2vf - vf + 2.4 = 1.2
vf = 1.2 - 2.4
vf = - 1.2
This answer is not possible, but 2 of us are getting the same answer. The other person is someone whose math I would never question. She rarely makes an error. And I do mean rarely. Could you check to see that you have copied this correctly?
