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77julia77 [94]
2 years ago
13

An ordinary ruler is used to measure the area and its error of a rectangle. It is found that their sides are 5.0 cm long and 2.0

cm width. The error in area (in cm) is​
Physics
1 answer:
Elina [12.6K]2 years ago
3 0

Answer:

You need to know the accuracy to which you can read the ruler:

Suppose that you can read the read the ruler to the nearest milimeter

A = L * W     your calculated area of the rectangle

A + ΔA = (L + ΔL) * (W + ΔW) = L W + L ΔW + W * ΔL + ΔL ΔA

Or ΔA =  L ΔW + W ΔL

Where we have subtracted A = L * W and the term ΔL * ΔA is very small

So (5 + .1) * (2 + .1) - 5 * 2 = .1 * 2 + .1 * 5 = .7 cm^2

Then you report A = 10 cm^2 +- .7 cm^2    including the - sign for completeness

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The bacteria that doesn’t live in extreme conditions is Eubacteria
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The heat capacity of object B is twice that of object A. Initially A is at 300 K and B at 450 K. They are placed in thermal cont
ivann1987 [24]

Answer:

The final temperature of both objects is 400 K

Explanation:

The quantity of heat transferred per unit mass is given by;

Q = cΔT

where;

c is the specific heat capacity

ΔT is the change in temperature

The heat transferred by the  object A per unit mass is given by;

Q(A) = caΔT

where;

ca is the specific heat capacity of object A

The heat transferred by the  object B per unit mass is given by;

Q(B) = cbΔT

where;

cb is the specific heat capacity of object B

The heat lost by object B is equal to heat gained by object A

Q(A) = -Q(B)

But heat capacity of object B is twice that of object A

The final temperature of the two objects is given by

T_2 = \frac{C_aT_a + C_bT_b}{C_a + C_b}

But heat capacity of object B is twice that of object A

T_2 = \frac{C_aT_a + C_bT_b}{C_a + C_b} \\\\T_2 = \frac{C_aT_a + 2C_aT_b}{C_a + 2C_a}\\\\T_2 = \frac{c_a(T_a + 2T_b)}{3C_a} \\\\T_2 = \frac{T_a + 2T_b}{3}\\\\T_2 = \frac{300 + (2*450)}{3}\\\\T_2 = 400 \ K

Therefore, the final temperature of both objects is 400 K.

4 0
2 years ago
Sitting in a chairlift, Rebecca has a gravitational potential energy of 5,997.6
stira [4]

Answer:

B) 12 m

Explanation:

Gravitational potential energy is:

PE = mgh

Given PE = 5997.6 J, and m = 51 kg:

5997.6 J = (51 kg) (9.8 m/s²) h

h = 12 m

8 0
3 years ago
The kitchen in your house measures 10 ft by 10 ft. You need to have 50 footcandles of illumination in the room. How many 60 watt
tekilochka [14]

Answer:

<u>6 bulbs</u> are needed to illuminate the room.

Explanation:

Given:

Measurement of kitchen (A) = 10 ft by 10 ft = 100 sq. ft

Number of footcandles (n) = 50

Lumens emitted by 1 bulb = 834

Number of bulbs (N) = ?

We are also given,

1 foot candle = 1 lumen/sq. ft

So, 50 foot candles = 50 lumens/sq. ft

Now, for an area of 1 sq. ft 50 lumens are emitted.

So, for an area of 100 sq. ft, lumens emitted = 50 × 100 = 5000 lumens

Now, one bulb emits = 834 lumes

Therefore, number of bulbs required for emitting 5000 lumens is given as:

N=\frac{Number\ of\ lumens}{Number\ of\ lumens\ by\ 1\ bulb}\\\\N=\frac{5000}{834}=5.995\approx6

So, 6 bulbs are needed to illuminate the room.

7 0
3 years ago
The atmosphere of Mars is almost all carbon dioxide and the average surface pressure is 610 Pa (as compared with 101,000 Pa on E
Karolina [17]

Answer:

   z = 3,737 10⁵ m

Explanation:

a) As they indicate that the atmosphere behaves like an ideal gas, we can use the equation

          P V = n R T

          P = (n r / V) T

We replace

         P = (n R / V) T₀ e^{- C z}

b) Let's apply this equation in the points

Lower

        .z = 0

         P₀ = 610 Pa

         P₀ = (nR / V) T₀

Higher.

         P = 10 Pa

          P = (n R / V) T₀ e^{- C z}

We replace

        P = P₀ e^{- C z}

        e^{- C z} = P / P₀

        C z = ln P₀ / P

        z = 1 / C ln P₀ / P

Let's calculate

        z = 1 / 1.1 10⁻⁵ ln (610/10)

        z = 3,737 10⁵ m

4 0
3 years ago
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