Rock is completely immersed in hot water. By the second law of thermodynamics, thermal energy or heat is transferred from substance with higher temperature to substance with lower temperature until they come to thermal equilibrium i.e. both at same temperature.
It is given here that rock is at 20°C which is at lower temperature than water at 80°C. ∴Heat or thermal energy flows from water to rock. So, right choice is-
A. The water gives the rock thermal energy and gets no thermal energy in return.
The purpose of the fraud fighter or also known as black
light machine is that it has the ability to check counterfeited bills. It is
designed to be a detector with the counterfeited bills, plus, it is a way of
verification. It is composed of a UV light, where in, making it have the
ability to detect the counterfeited bills which is its task to do.
The answer is C. ionic compounds, compared to another hard compound which is the covalent bond, the structure of the ionic compound is lattice or crystalline in form thus less room for imperfections on its structure compared to the latter choices.
Answer:
0.001 s
Explanation:
The force applied on an object is equal to the rate of change of momentum of the object:
where
F is the force applied
is the change in momentum
is the time interval
The change in momentum can be written as
where
m is the mass
v is the final velocity
u is the initial velocity
So the original equation can be written as
In this problem:
m = 5 kg is the mass of the fist
u = 9 m/s is the initial velocity
v = 0 is the final velocity
F = -45,000 N is the force applied (negative because its direction is opposite to the motion)
Therefore, we can re-arrange the equation to solve for the time:
