Decreasing the trains velocity will DECREASE the kinetic energy
Resistance = (voltage) / (current)
Resistance = (120 V) / (0.5 A)
<em>Resistance = 240 ohms</em>
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Know what ? There might be too much information given in this question. I want to check, because it's possible that it might not even all fit together.
To calculate my answer, I only used the voltage and the current. I didn't use the "60 watts", and I'm curious to know whether it even fits with the given voltage and current.
Power = (voltage) times (current).
Power = (120 V) times (0.5 A)
Power = 60 watts
Well gadzooks and sure enough ! The three numbers given in the question all go together nicely.
And not only THAT !
The answer could have been calculated by using ANY TWO of them.
Answer:
a)
1.35 kg
b)
2.67 ms⁻¹
Explanation:
a)
= mass of first body = 2.7 kg
= mass of second body = ?
= initial velocity of the first body before collision = 
= initial velocity of the second body before collision = 0 m/s
= final velocity of the first body after collision =
using conservation of momentum equation

Using conservation of kinetic energy

b)
= mass of first body = 2.7 kg
= mass of second body = 1.35 kg
= initial velocity of the first body before collision = 4 ms⁻¹
= initial velocity of the second body before collision = 0 m/s
Speed of the center of mass of two-body system is given as
ms⁻¹