Answer: Hand tools are necessary for daily activities.
Explanation:
The hand tools are useful for day to day activities they aid in pouring substances, holding things, mixing substances, cleaning and for other purposes. In a chemical laboratory the hand tools like test tube holders can help in holding the chemicals. In a medical laboratory the forceps can be useful in holding and cutting the sections without causing any harm to the hands. Hand tools avoid the direct contact with the microorganisms in medical laboratory thus protect against infections. Hand tools aid in surgical operations and they help in avoiding direct contact with the blood vessels and organs preventing contamination and infections.
We can base this on the equation of thermal expansion.
ΔL = L₀αΔT
where
ΔL is the expansion of length upon heating
L₀ is the initial length
α is the coefficient of linear expansion
ΔT is the temperature difference
So, if α for Aluminum is greater than α for Copper, then after heating, aluminum would be longer than copper.
Lamina occupies x² + y² = 14y. Outside circle is x² + y² = 49
To find the mass of lamina, integrate given density function over the region
m = ∫∫D P(x, y) dA
Subtitute x = r cosФ and y = r sinФ in x² + y² = 14y
and x² + y² = 49
x² + y² = 14y
(r cosФ)² + ( rsinФ)² = 14(rsinФ)
r² = 14r sin Ф
x² +y² = 49
r² = 49
r = 7
Cntre mass (-x. -y)
-x= i/m ∫∫D xp(x,y) dA = 1/m∫∫ (r cosФ) p( r, Ф)r
dr dФ
-y = 1/m∫∫D yp(x, y) dA = 1/m ∫∫D (r sinФ) p(r, Ф) r drФ
where m = ∫∫D p(x, y) dA
Answer: Symbol A
Explanation:
The four symbols described here represent:
- Symbol A shows two dots and a line draw from one not connected to the other. --> this is an open switch. A switch is component of a circuit that is used to open/close the circuit in order to interrupt/allow the flow of current through the circuit. In this case, the switch is open, since the line does not connect the second dot.
- Symbol B shows two dots and a line draw from one connected to the other. --> this is the symbol used to represent the switch when it is closed, so it is a closed switch.
- Symbol C shows vertical lines in the pattern long, short, long, and short with a plus and minus symbol on it. --> this symbol represents a battery, which consists of two or more cells and provides the electromotive force that pushes the electrons along the circuit.
Therefore, the correct symbol representing the open switch is
Symbol A