Total weight = Volume × density
5) calculate weight of concrete slab by multiplying volume and their density in similar unit as Weight = Volume× density, density= 150lb/ cf, so total weight = 33 cf × 150 lb/cf = 4950 pounds or 2.475 short tons.
The amount of thermal energy needed is 626.6 J
Explanation:
When a certain amount of heat energy Q is supplied to a substance, the temperature of the substance increases according to the equation
where
m is the mass of the substance
is the specific heat capacity of the substance
is the change in temperature
In this problem,
m = 4.5 kg is the mass
is the specific heat capacity of the substance
is the change in temperature of the substance
Solving for Q,
(Note that the substance cannot be water, since specific heat capacity of water is 
Learn more about specific heat capacity:
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The correct answer is the Type of batteries
Explanation:
In an experiment, it is normal the researcher modifies one variable, in this case, the number of batteries (independent variable), and this variable affects the variable tested, in this case, the brightness of the bulb (dependent variable).
However, other factors or variables should be constant to guarantee the results are reliable. In this context, one factor that the student should keep constant is the type of batteries he uses because this is not one of the main variables and therefore it is not expected he changes this on purpose or this is affected by other variables. Moreover, by making any change the experiment can be negatively affected. For example, batteries might differ in their power capacity this can affect the brightness of the bulbs.
Answer:
`1. charge Q, on the capacitor increases, while the current will decrease
2. τ = t = secs
Explanation:
1. consider RC of a circuit to be am external source
voltage across the circuit is given as
v =v₀(1 - 
)
where v = voltage
v₀ = peak voltage
t = time taken
τ= time constant
as the charge across the capacitor increases, current decreases
the charge across the circuit is given as
Q= Q₀(1 - )
charge Q is inversely proportional to the current I
hence the charge across the circuit increases
2. τ = RC
unit of time constant, τ,
= Ω × F
=
ˣ 
=
=
τ = t = secs
