1. A jogger jogs 25 m East, stops to rest, then continues for 10 more meters

A slice of pizza has 500 kcal. If we could burn the pizza and use all the heat to warm a 50-L container of cold water, what woul

topjm [15]

Answer:

increase in temperature of water is 10° C

Explanation:

Given data

pizza = 500 kcal = 500000 calories

cold water = 50 L

to find out

increase in temperature of water

solution

we know heat formula that is

heat = m × specific heat × Δt

here m is mass = 50000 gram and Δt is change in temperature

and specific heat = 1 cal / gram C

so put here all value and find Δt

500000 = 50000 × 1 × Δt

Δt = 10° C

so increase in temperature of water is 10° C

4 0

3 years ago

Read 2 more answers

The interior space of large box is kept at 30 C. The walls of the box are 3 m high and have a ‘sandwich’ construction consisting

White raven [17]

Answer:

$\frac{\dot Q}{A} =20.129\ W.m^{-2}$

$T_1=27.58\ ^{\circ}C$ & $T_2=2.41875\ ^{\circ}C$

Explanation:

Given:

interior temperature of box, $T_i=30^{\circ}C$

height of the walls of box, $h=3\ m$

thickness of each layer of bi-layered plywood, $x_p=1.25\ cm=0.0125\ m$

thermal conductivity of plywood, $k_p=0.104\ W.m^{-1}.K^{-1}$

thickness of sandwiched Styrofoam, $x_s=5\ cm=0.05\ m$

thermal conductivity of Styrofoam, $k_s=0.04\ W.m^{-1}.K^{-1}$

exterior temperature, $T_o=0^{\circ}C$

From the Fourier's law of conduction:

$\dot Q=\frac{dT}{(\frac{x}{kA}) }$

$\dot Q=\frac{dT}{R_{th} }$ ....................................(1)

Now calculating the equivalent thermal resistance for conductivity using electrical analogy:

$R_{th}=R_p+R_s+R_p$

$R_{th}=\frac{x_p}{k_p.A}+\frac{x_s}{k_s.A}+\frac{x_p}{k_p.A}$

$R_{th}=\frac{1}{A} (\frac{x_p}{k_p}+\frac{x_s}{k_s}+\frac{x_p}{k_p})$

$R_{th}=\frac{1}{A} (\frac{0.0125}{0.104}+\frac{0.05}{0.04}+\frac{0.0125}{0.104})$

$R_{th}=\frac{1.4904}{A}$ .....................(2)

Putting the value from (2) into (1):

$\dot Q=\frac{30-0}{\frac{1.4904}{A} }$

$\dot Q=\frac{30\ A}{1.4904}$

$\frac{\dot Q}{A} =20.129\ W.m^{-2}$ is the heat per unit area of the wall.

The heat flux remains constant because the area is constant.

For plywood-Styrofoam interface from inside:

$\frac{\dot Q}{A} =k_p.\frac{T_i-T_1}{x_p}$

$20.129=0.104\times \frac{30-T_1}{0.0125}$

$T_1=27.58\ ^{\circ}C$

&For Styrofoam-plywood interface from inside:

$\frac{\dot Q}{A} =k_s.\frac{T_1-T_2}{x_s}$

$20.129=0.04\times \frac{27.58-T_2}{0.05}$

$T_2=2.41875\ ^{\circ}C$

4 0

3 years ago

One characteristic of mass wasting processes is that they a. only operate on steep slopes. b. move materials very slowly. c. ope

lord [1]

Answer:

One characteristic of mass wasting processes is that they move materials relatively short distances compared to streams. - d.

4 0

3 years ago

What is the average power consumption in watts of an appliance that uses 5.00 kWh of energy per day? How many joules of energy d

denpristay [2]

Answer:

(A) power = 0.208 kW = 208 watts

(B) energy = 6.6 x 10^{9} joules

Explanation:

energy consumed per day = 5 kWh

(a) find the power consumed in a day

1 day = 24 hours

power = \frac{energy}{time}

power = \frac{5}{24}

power = 0.208 kW = 208 watts

(b) find the energy consumed in a year

assuming it is not a leap year and number of days = 365 days

1 year = 365 x 24 x 60 x 60 = 31,536,000 seconds

energy = power x time

energy = 208 x 31,536,000

energy = 6.6 x 10^{9} joules

5 0

3 years ago

Does the KE of a car change more when it accelerates from 22 km/h to 32 km/h or when it accelerates from 32 km/h to 42 km/h

mote1985 [20]

Answer:

The change in kinetic energy (KE) of the car is more in the second case.

Explanation:

Let the mass of the car = m

initial velocity of the first case, u = 22 km/h = 6.11 m/s

final velocity of the first case, v = 32 km/h = 8.89 m/s

change in kinetic energy (K.E) = ¹/₂m(v² - u²)

ΔK.E = ¹/₂m(8.89² - 6.11²)

= 20.85m J

initial velocity of the second case, u = 32 km/h = 8.89 m/s

final velocity of the second case, v = 42 km/h = 11.67 m/s

change in kinetic energy (K.E) = ¹/₂m(v² - u²)

ΔK.E = ¹/₂m(11.67² - 8.89²)

= 28.58m J

The change in kinetic energy (KE) of the car is more in the second case.

6 0

3 years ago