Answer:
Force on the object is 20 N
Explanation:
As we know that work done to raise the book from initial position to final position is known as potential energy stored in it
So here we know that

here we know that
U = 30 J
s = displacement = 1.5 m
so we have


Answer:
<h2> r=mv/Be</h2>
Explanation:
If a positive charge enters a magnetic field at 90 degrees the charge is deflected in a circular path by a force that acts perpendicular to it in line with Flemings right-hand rule
to derive the radius of the path of the charge we apply
F= mv^2/r=Bev
where
m= mass of the electronic charge
e=charge
B=magnetic field
v=average speed
r=radius
rearranging we have
r=mv^2/Bev
r=mv/Be
The ampere (symbol: A) is the SI base unit of electric current equal to one coulomb per second.
The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross section, and placed 1 meter apart in vacuum, would produce between these conductors a force equal to 2 times 10–7 newton per meter of length.
Electric current is the time rate of change or displacement of electric charge.
One ampere represents the rate of 1 coulomb of charge per second.
The ampere is defined first (it is a base unit, along with the meter, the second, and the kilogram), without reference to the quantity of charge.
The unit of charge, the coulomb, is defined to be the amount of charge displaced by a one ampere current in the time of one second.
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