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vladimir2022 [97]

2 years ago

11

Two cars are travelling in the same direction on a road. The blue car is travelling at 50 m/s in front of the red car, which is

travelling at 75 m/s. What is their relative speed? *

1 answer:

Anestetic [448]2 years ago

6 0

Explanation:

The speed of the red car, relative to the blue car, is:

v = 75 m/s − 50 m/s

v = 25 m/s

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A boy runs 400m at an average speed of 4.0m/s he runs the first 200m in 40 s how long does he take to run the second 200m?

IRISSAK [1]

If he runs at the same speed he will cover next 200m in 40s
that is at the average of 4.0m

8 0

3 years ago

Q 24, 25, 26 i dont get them and need answers for it

Alexandra [31]

Answer:

24) W = 75 [J]; 25) W = 1794[J]; 26) n = 8.8 (times) or 9 (times)

Explanation:

24) This problem can be solved by means of the following equation.

$DU = Q-W\\$

where:

DU = internal energy difference [J]

Q = Heat transfer [J]

W = work [J]

Since there are no temperature changes the internal energy change is equal to zero

DU = 0

therefore:

$Q = W\\$

The work is equal to the heat transfered, W = 75 [J].

25) The heat transfer can be calculated by means of the following equation.

$Q = m*c_{p}*DT\\where:\\m = mass = 0.4[kg]\\c_{p} = specific heat = 897[J/kg*K]\\DT= 5 [C]$

Q = 0.4*897*5 = 1794[J]

Work is equal to heat transfer, W = 1794[J]

26) Each time the bag falls the potential energy is transformed into heat energy, which is released into the environment. In this way the potential energy is equal to the developed heat.

$E_{p}=Q\\\\E_{p}=m*g*h$

where:

m = mass = 0.5[kg]

g = gravity = 9.81[m/s^2]

h = 1.5 [m]

$E_{p}=0.5*9.81*1.5\\E_{p}=7.36[J]$

The heat developed can be calculated by means of the following equation.

$Q=m*c_{p}*DT\\Q=0.5*130*1\\Q=65[J]$

The number of times will be calculated as follows

n = 65/7.36

n = 8.8 (times) or 9 (times)

7 0

3 years ago

You are on the south bank of the river in your canoe you need to reach the north bank you know that you can row your canoe at 2

Anna71 [15]

Answer:

(θ) = 60°

Explanation:

Given:

Speed of canoe Vc = 2 m/s

Speed of River Vr = 1 m/s

Computation:

Vc (Cosθ) = Vr

2 (Cosθ) = 1

(Cosθ) = 1 / 2

(Cosθ) = (Cos60)

(θ) = 60°

3 0

2 years ago

According to the diagram of the electromagnetic spectrum shown, what would best represent the

iren2701 [21]

The best represent the size of visible light will be C. Protozoa

The electromagnetic spectrum, gives the overall distribution of electromagnetic radiation by the frequency or wavelength. All EM waves travel at the speed of light in a vacuum, but over a wide range of frequencies, wavelengths, and photon energies.

Visible light wavelengths cover the range of approximately 0.4 to 0.7 μm. electromagnetic spectrum that the human eye can see is the Visible light. Visible light is a form of electromagnetic (EM) radiation, along with radio waves, infrared, ultraviolet, X-rays, and microwaves. the wavelengths that are visible to most human eyes is generally known as Visible light

the best represent the size of visible light is Protozoa, According to the diagram of the electromagnetic spectrum shown,

Learn more about electromagnetic spectrum here brainly.com/question/25847009

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6 0

9 months ago

You have 4.9 g of an unknown substance. To identify the substance, you decide to measure its specific heat and find that it requ

kifflom [539]

The unknown substance can be lithium, which has a specific heat capacity of approximately $3.5 J/gK$ .

Explanation:

When heat energy is supplied to a certain substance, the temperature of the substance increases according to the equation:

$Q=mC_s \Delta T$

where

Q is the amount of energy supplied

m is the mass of the sample

$C_s$ is the specific heat capacity of the substance

$\Delta T$ is the change in temperature

In this problem, we have

m = 4.9 g is the mass

Q = 668.85 J is the specific heat capacity

$\Delta T = 39 K$ is the change in temperature

Solving for $C_s$ , we find the specific heat capacity of the substance:

$C_s = \frac{Q}{m\Delta T}=\frac{668.85}{(4.9)(39)}=3.5 J/gK$

Looking at tables of specific heat capacity, we can see that the unknown substance can be lithium, which has a specific heat capacity of approximately $3.5 J/gK$ .

Learn more about specific heat capacity:

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3 0

2 years ago