Answer:
(a) the runner's kinetic energy at the given instant is 308 J
(b) the kinetic energy increased by a factor of 4.
Explanation:
Given;
mass of the runner, m = 64.1 kg
speed of the runner, u = 3.10 m/s
(a) the kinetic energy of the runner at this instant is calculated as;
(b) when the runner doubles his speed, his final kinetic energy is calculated as;
the change in the kinetic energy is calculated as;
Thus, the kinetic energy increased by a factor of 4.
Answer:
Explanation:
Given data
Coefficient of performance of a residential heat pump=1.6
Electrical power P=4kW
Required
Heat Q
Solution
The rate of heat produced is given as
Substitute the given values
So
Answer:
E.) conservation of angular momentum
Explanation:
The angular momentum is defined as:
x
where is the radius of the star,
is the mass and
the angular velocity.
and angular momentum is an amount that is conserved, so the angular momentum before the star is compressed must be equal to the angular momentum after the star was compressed:
x
x
the second radius is smaller than the first radius, since the star shrinked, the second angular velocity must be greater that the first.
In other words, the angular velicity increases as the star shrinks because of the conservation of angular momentum.