Answer: (d)
Explanation:
Given
Mass of object 
Speed of object 
Mass of object at rest 
Suppose after collision, speed is v
conserving momentum

Initial kinetic energy

Final kinetic energy

So, it is clear there is decrease in kinetic energy . Thus, energy decreases and velocity becomes 2 m/s.
Answer:
Temperature, T = 3.62 kelvin
Explanation:
It is given that,
Total number of gas molecules, 
Her body is converting chemical energy into thermal energy at a rate of 125 W, P = 125 W
Time taken, t = 6 min = 360 s
Energy of a gas molecules is given by :

, k is Boltzmann constant


T = 3.62 K
So, the temperature increases by 3.62 kelvin. Hence, this is the required solution.
Because: Some of the work done by the machine is used to overcome the friction created by the use of the machine. ... Work output can never be greater than work input. Machines allow force to be applied over a greater distance, which means that less force will be needed for the same amount of work.
Answer:
9155 years old
Explanation:
We use the following expression for the decay of a substance:

So we first estimate the value of k knowing that the half-life of the C14 is 5730 years:

so, now we can estimate the age of the artifact by solving for"t" in the equation:

which we can round to 9155 years old.