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Agata [3.3K]
3 years ago
15

What is the amount of heat, in calories, given off from a 5 g piece of aluminum when it cools from 80°C to 20°C? The specific he

at capacity of aluminum is 0.215 cal/g∙°C. Show your work.
Physics
1 answer:
vagabundo [1.1K]3 years ago
8 0

Answer:

Q (heat) = S * m * (T2 - T1)  where Q is heat gained (loss), S the specific heat capacity of the substance and T2, T1 are the final and initial temps

Q = .215 cal  / (g deg C) * 5 g * (20 - 80) deg C = -64.5 cal

Since the question specifies the heat emitted, then  64.5 cal is the

heat emitted (loss).

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A triangular plate with height 6 ft and a base of 7 ft is submerged vertically in water so that the top is 2 ft below the surfac
xenn [34]

Answer:

62.5\int\limits^6_0 {(\frac{7}{6}y^{2}-\frac{49}{3}y+56)  } \, dy = 7875 lb

Explanation:

For this problem to be easier to calculate, we can represent the triangle as a right triangle whose right angle is located at the origin of a coordinate system. (See picture attached).

With this disposition of the triangle, we can start finding our integral. The hydrostatic force can be set as an integral with the following shape:

\int\limits^a_bγhxdy

we know that γ=62.5 lb/ft^{3}

from the drawing, we can determine the height (or depth under the water) of each differential area is given by:

h=8-y

x can be found by getting the equation of the line, which we'll get by finding the slope of the line and using one of the points to complete the equation:

m=\frac{y_{2}-y_{1}}{x_{2}-x{1}}

when substituting the x and y-values given on the graph, we get that the slope is:

m=\frac{0-6}{7-0}=-\frac{6}{7}

once we got this slope, we can substitute it in the point-slope form of the equation:

y_{2}-y_{1}=m(x_{2}-x_{1})

which yields:

y-6=-\frac{6}{7}(x-0)

which simplifies to:

y-6=-\frac{6}{7}x

we can now solve this equation for x, so we get that:

x=-\frac{7}{6}y+7

with this last equation, we can substitute everything into our integral, so it will now look like this:

\int\limits^6_0{(62.5)(8-y)(-\frac{7}{6}y+7)}\,dy

Now that it's all written in terms of y we can now simplify it, so we get:

62.5\int\limits^6_0 {(\frac{7}{6}y^{2}-\frac{49}{3}y+56)}dy

we can now proceed and evaluate it.

When using the power rule on each of the terms, we get the integral to be:

62.5[\frac{7}{18}y^{3}-\frac{49}{6}y^{2}+56y]^{6}_{0}

By using the fundamental theorem of calculus we get:

62.5[(\frac{7}{18}(6)^{3}-\frac{49}{6}(6)^{2}+56(6))-(\frac{7}{18}(0)^{3}-\frac{49}{6}(0)^{2}+56(0))]

When solving we get:

62.5\int\limits^6_0 {(\frac{7}{6}y^{2}-\frac{49}{3}y+56)  } \, dy = 7875 lb

6 0
3 years ago
The acceleration due to gravity on the surface of Jupiter is about 2.5 times the acceleration due to gravity on Earth’s surface.
melisa1 [442]
The answer is 2.5 times heavier than on Earth !!

so the answer is C !!
4 0
3 years ago
Read 2 more answers
How much heat is needed to melt 16.5kg of silver that is initially at 20*c?
zubka84 [21]
The Specific Heat Capacity of silver is 230 J/kgK, melting point is 961.8 C so the difference is 941.8K. Now we simply do q=230J/kgK*16.5kg*941.8K and that is 3 574 131 J
8 0
3 years ago
Einstein and Lorentz, being avid tennis players, play a fast-paced game on a court where they stand 25.0 m from each other. Bein
Lerok [7]

Answer:

A) 199.78 J

B) 9.292x10^14 J

C) 4.2x10^7 m/s

D) 0.65 m

E) 1.13x10^-8 sec

D) 2.94x10^-9 sec

Explanation:

mass of ball = 0.0580 kg

A)

If smashed at v = 83.0 m/s, KE is

KE = 0.5mv^2

= 0.5 x 0.0580 x 83.0^2

= 199.78 J

B) if returned at v = 1.79×10^8 m/s, KE will be

KE = 0.5mv^2

= 0.5 x 0.0580 x (1.79×10^8)^2

= 9.292x10^14 J

C) during Einstein's return, velocity of rabbit relative to players is

Vr = 2.21×108 m/s

Rabbit's velocity relative to ball = 2.21×10^8 - 1.79×10^8

= 4.2x10^7 m/s

D) the rabbit's speed approaches the speed of light so we consider relativistic effect. The rabbit's measured distance is

l = l°( 1 - v^2/c^2)

= 2.5(1 - 2.21/3)

= 2.5 x 0.26

= 0.65 m

E) according to the players, the time taken by the rabbit is

t = d/v = 2.5/ 2.21×10^8

= 1.13x10^-8 sec

F) the time for rabbit as measured by rabbit is relativistic

t = t°( 1 - v^2/c^2)

= 1.13x10^-8 (1 - 2.21/3)

= 1.13x10^-8 x 0.26

= 2.94x10^-9 sec

7 0
3 years ago
You are working as a summer intern for the Illinois Department of Natural Resources (DNR) and are assigned to some initial work
hammer [34]

Answer:

1)   F = 71.6 N , 2)    F = 120.2 N , 3)  P_m=  68.600 Pa, 4)  V = 2.4210-5 m³

Explanation:

This is a problem of fluid mechanics, to find the force we must use its definition

         P = F / A

         F = P A

The area of ​​the circular pipe is

         A = π r² = π d²/4

The pressure is given by the expression

         P = P_atm + ρ g h

1) the force on the outer side is

       P = P_atm

we substitute in the expression of force

         F = P_atm π d² / 4

         

let's calculate

         F = 1,013 10⁵ π 0.03²/4

         F = 7.16 10¹ N

         F = 71.6 N

2) the force on the inner side

  the pressure

       P = P_atm + ρ g h

       P = 1,015 10⁵ + 1,000 9.8 7

        P = 1,701 10⁵ Pa

        F = 1,701 10⁵ π 0.03² / 4

        F = 1,202 10²

        F = 120.2 N

3) manometric pressure

       Pm = ρ g h

       P m = 1000 9.8  7

       P_m=  68.600 Pa

4) In this part they ask for the volume that comes out in time t= 3 h

   to calculate this volume we can use the flow ratio

         Q = A v

          V t = A v

          V = A v / t

sent is the velocity of the water that comes out, to calculate it we use the Bernoulli equation

we will use index 1 for the lake surface and ionice 2 apa the position of the plug

           P₁ + ρ g v₁² + ρ g y₁ = P₂ + ρ g v₂² + ρ g y₂

As the lake has much more capacity than the pipeline, the velocity of the surface of the lake is peeling, in this case we approximate it steel

           (P₁-P₂) + ρ G (y₁ -y₂) = ρ g v₂²

           1000 9.8 v₂² = ρ g h + 1000 9.8 (7-0)

             9800 v₂² = 1000 9.8 7 + 68600

              v₂ = √ (137200)

               v₂ = 370.4 m / s

             t = 3 h (3600s / h) = 10800 s

     

we substitute in the volume equation

             V = π d²/4   370.4 / 10800

             V = 2.4210-5 m³

4 0
2 years ago
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