Amit has found a rock in his backyard and would like to measure its mass, volume, and density. What tools can he use to perform
1 answer:
Answer: a graduated cylinder and balance
A rock has an irregular shape. so, it would be difficult to measure using a meter stick. most convenient method to find the volume would be using a graduated cylinder. we can take a fixed volume of water in the cylinder. then drop rock into it. note the new raised volume. Subtract the initial volume from final to find the volume of rock.
Using balance, mass of the rock can be measured.
we can calculate the density using the following formula:
Therefore, we need only two tools, a graduated cylinder and a balance to measure mass, volume and density of a rock.
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(a) The electrons move horizontally from west to east, while the magnetic field is directed downward, toward the surface. We can determine the direction of the force on the electron by using the right-hand rule:
- index finger: velocity --> due east
- middle finger: magnetic field --> downward
- thumb: force --> due north
However, we have to take into account that the electron has negative charge, therefore we have to take the opposite direction: so, the magnetic force is directed southwards, and the electrons are deflected due south.
b) From the kinetic energy of the electrons, we can find their velocity by using
where K is the kinetic energy, m the electron mass and v their velocity. Re-arranging the formula, we find
The Lorentz force due to the magnetic field provides the centripetal force that deflects the electrons:
where
q is the electron charge
v is the speed
B is the magnetic field strength
m is the electron mass
r is the radius of the trajectory
By re-arranging the equation, we find the radius r:
And finally we can calculate the centripetal acceleration, given by:
- index finger: velocity --> due east
- middle finger: magnetic field --> downward
- thumb: force --> due north
However, we have to take into account that the electron has negative charge, therefore we have to take the opposite direction: so, the magnetic force is directed southwards, and the electrons are deflected due south.
b) From the kinetic energy of the electrons, we can find their velocity by using
where K is the kinetic energy, m the electron mass and v their velocity. Re-arranging the formula, we find
The Lorentz force due to the magnetic field provides the centripetal force that deflects the electrons:
where
q is the electron charge
v is the speed
B is the magnetic field strength
m is the electron mass
r is the radius of the trajectory
By re-arranging the equation, we find the radius r:
And finally we can calculate the centripetal acceleration, given by: