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IRINA_888 [86]
3 years ago
14

8. A car travels from Town A to Town B on one road at different speeds and stops at red lights. If you know the distance between

the towns and the total time of the trip you can calculate the
Physics
1 answer:
ryzh [129]3 years ago
4 0

Answer:

The velocity

Explanation:

The difference between speed and velocity is the following:

- Speed is defined as the ratio between the total distance covered by an object and the time taken:

speed = \frac{distance}{time}

and it is a scalar.

In this problem, we cannot calculate the speed of the car, because we don't know exactly what is the distance covered by the car (we only know the distance between town A and town B, but we don't know if the car has travelled on a straight path or not, so we don't know the distance it has covered)

- Velocity is defined as the ratio between the displacement and the time taken:

velocity=\frac{displacement}{time}

(note that velocity is a vector)

Displacement is the shortest distance (straight line) between the final and the initial point of the motion: in this case, it corresponds to the distance between town A and town B, which we know. Since we also know the time of the trip, this means that we can calculate the velocity of the car.

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6. The two ends of an iron rod are maintained at different temperatures. The amount of heat thatflows through the rod by conduct
motikmotik

Answer:

20cal/s

Explanation:

Question:

There are two questions. The first one has been answered:

From the formular, Power = Q/t = (kA∆T)/l

the amount heat depends on the duration of time interval, length of the iron rod, the thermal conductivity of iron and the temperature difference between the ends of the rod.

The amount of heat that flows through the rod by conduction during a given time interval does not depend upon the mass of the iron rod (D).

Second question:

The ends of a cylindrical steel rod are maintained at two different temperatures. The rod conducts heat from one end to the other at a rate of 10 cal/s. At what rate would a steel rod twice as long and twice the diameter conduct heat between the same two temperatures?

Solution:

Power = 10cal/s

Power = energy per unit time = Q/t

Where Q = energy

Power = (kA∆T)/l

k = thermal conductivity of iron

A = area

Area = πr^2

r = radius

Diameter = d = 2r

r = d/2

Area = (πd^2)/4

Length = l

∆T = change in temperature

10 = (kA∆T)/l

For a steel rod with length doubled and diameter doubled:

Let Length (L) = 2l

Diameter (D)= 2d

Area = π [(2d)^2]/4 = (π4d^2)/4

Area = 4(πd^2)/4

Using the formula Power = (kA∆T)/l, insert the new values for A and l

Power = [k × 4(πd^2)/4 × ∆T]/2l

Power = [4k((πd^2)/4) ∆T]/2l

Power = [(4/2)×k((πd^2)/4) ∆T]/l

Power = [2k(A) ×∆T]/l = 2(kA∆T)/l

Power of a steel that has its length doubled and diameter doubled = 2(kA∆T)/l

Recall initial Power = (kA∆T)/l = 10cal/s

And ∆T is the same

2[(kA∆T)/l] = 2 × 10

Power of a steel that has its length doubled and diameter doubled = 20cal/s

4 0
3 years ago
Using a refracting telescope, you observe the planet Mars when it is 1.99×1011 m from Earth. The diameter of the telescope's obj
Rudik [331]

The minimum feature size, in kilometers, on the surface of Mars that your telescope can resolve for you is  140km.

<h3>What is telescope?</h3>

Telescope is device through which we can see the distant objects very clearly as it seems like they are some meters away.

Distance of the Mars from the Earth D = 1.99 x 10¹¹ m

Diameter of telescope's objective lens d = 0.977 m

The wavelength of light λ in m, λ = 563nm = 563 x 10⁻⁹ m

The distance y or the minimum feature size  =1.22λD/d

Substitute the value, we get

y = 1.22 x 563 x 10⁻⁹ x 1.99 x 10¹¹ /0.977

y = 140 km (approximately)

Thus, the minimum feature size, in kilometers, on the surface of Mars that your telescope can resolve for you is  140km.

Learn more about Telescope.

brainly.com/question/556195

#SPJ1

5 0
2 years ago
What is the independent variable? What is the dependent variable? Please help!
e-lub [12.9K]

graphic too wide.

indep variable is one you control

dep var is what happens

7 0
3 years ago
A 5.00 kg rock whose density is 4300 kg/m3 is suspended by a string such that half of the rock's volume is under water. You may
12345 [234]

Answer:

The tension on the string is  T  =  43.302 \ N

Explanation:

From the question we are told that

    The mass of the rock is m_r = 5.00 \ kg =  5000 \ g

       The density of the rock is \rho  =  4300 \ kg/m^3 =  4.3 g/dm^3

       

Generally the volume of the rock is mathematically evaluated as

          V    =  \frac{m_r}{\rho}

substituting values

        V    =  \frac{5000}{4.3}

       V    =  1162.7 \  dm^3

The volume of the rock immersed in water is

      V_w = \frac{V}{2}  

substituting values

     V_w = \frac{1162.7 }{2}

     V_w = 581.4 \ dm^3

mass of water been displaced by the this volume is

     m_w  = V_w     According to Archimedes principle

=>   m_w =  581.4 \ g

     m_w =  0.5814 \ kg

The weight of the water displace is  

      W _w =  m_w  * g

      W _w =  0.5814  * 9.8

      W _w = 5.698 \ N

The actual weight of the rock is  

      W_r  =  m_r * g

     W_r  =  5.0 *  9.8

     W_r  =  49.0 \ N

The tension on the string is

       T  = W_r - W_w

substituting values

       T  = 49.0 -  5.698

       T  =  43.302 \ N

4 0
3 years ago
What would happen to the fossil when weathering occurs. Would it survive ? ASAP
Kamila [148]
Yes it would servive beacuse the fossils are dug down into the rockand unable to move
6 0
3 years ago
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