Answer:
copper wire, metal nail, battery
Explanation:
To create an electromagnet, the material to be magnetized (such as a metal nail) is placed inside a solenoid, the ends of the coils are connected to a circuit that includes a battery.
Current is allowed to flow for a few seconds and then cut off. The polarity of the magnet depends on the direction of flow of current in the solenoid.
The smallest atomio radius is helium
Answer: c. 179 kJ/mol
Explanation:
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to Hess’s law, the chemical equation can be treated as algebraic expressions and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
Given:
(1)
(2)
(3)
(4)
On subtracting eq (1) from eq (2) we have:
- 


Hence the enthalpy change for the raection is 179.0 kJ/mol.
F = (mass)(acceleration) = ma
m = 55 kg
Vi = 20 m/s
t = 0.5 s
Vf = 0 m/s (since she was put to rest)
a=(Vf-Vi)/t
a=(0-20)/5
a = 40 m/s^2 (decelerating)
F = ma = (55 kg)(40 m/s^2)
F = 2200 N