Answer: 4.45m/s
Explanation:
I assume we're solving for her speed.
400m x 4 laps = 1600m
1600m / 6 minutes = 266.67m/min
(266.67m/min) x (1 minute/60 seconds) = 4.45m/s
266.67/60 = 4.45m/s
Answer:
The free body diagram of John is shown in the attached figure (in the FBD john's mass is supposed to be concentrated at his center of mass and FBD is made of center of mass)
b) As shown in the FBD the ground reaction forces are:
i) In X direction 
ii) In Y direction 
c) The respective accelerations in x and y direction's is calculated by newton's second law as indicated under
<em>The correct option is</em> D. The initial momentum of the blue and green train combined during the collision is 200 kgm/s.
<h3>
Initial momentum of the blue and green train</h3>
Apply the principle of conservation of linear momentum as follows;
Pi = m1v1 + m2v2
where;
- m1 is mass of blue train
- m2 is mass of green train
- v1 is velocity of blue train
- v2 is velocity green train
- Pi is the initial momentum of the two trains
Pi = (50 x 4) + 30(0)
Pi = 200 kgm/s
Thus, the initial momentum of the blue and green train combined is 200 kgm/s.
Learn more about momentum here: brainly.com/question/7538238
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