All categories

3 years ago

In which of the following situations is the Doppler effect absent?

1 answer:

4 0

The source and the observer are moving towards each other. The observer is moving toward the source. The source is moving away from the observer

You might be interested in

Consider an elevator with a table and a book on top of the table. The mass of the table is 10kg and the mass of the book is 2kg.

Step2247 [10]

Newton's second law allows us to find the force of the block on the table is 126 N

Newton's second law says that the net force is proportional to the product of the mass and the acceleration of the body

Σ F = m a

Where the bold letters indicate vectors, m is the mass and the acceleration of the body

A free body diagram is a diagram where the forces are represented without the details of the bodies, in the attached we can see a free body diagram of the system.

Let's start by finding the acceleration of the elevator with kinematics

v = v₀ + a t

a = $\frac{v-v_o}{a}$

Where v and v₀ are the current and initial velocity, respectively, at acceleration and t is the time

a = $\frac{8-1}{2}$

a = 3.5 m / s²

Let's write Newton's second law for each body

The book

N₂ - W₂ + N₁ = m a

Table

N₁ - W₁ - W₂ = M a

W₁ = Mg

W₂ = mg

N₁ = (M + m) g + M a

N₁ = (10 + 2) 9.8 + 10 3.5

N₁ = 152.6 N

This is the reaction of the earth to the support of the block and the table

N₂ = ma + m g - N₁

N₂ = m ( a +g) - N₁

N₂ = 2 (3.5 + 9.8) - 152.6

N₂ = 26.6 - 152.6

N₂ = -126 N

The negative sign indicates that the direction is opposite to the one assigned, this is the action of the block on the table.

In conclusion using Newton's second law we can find the forces of the block on the table is 126 N

Learn more here: brainly.com/question/19860811

4 0

3 years ago

A helicopter starting on the ground is rising directly into the air at a rate of 25 ft/s. You are running on the ground starting

rusak2 [61]

Answer:

The rate of change of the distance between the helicopter and yourself (in ft/s) after 5 s is $\sqrt{725}$ ft/ sec

Explanation:

Given:

h(t) = 25 ft/sec

x(t) = 10 ft/ sec

h(5) = 25 ft/sec . 5 = 125 ft

x(5) = 10 ft/sec . 5 = 50 ft

Now we can calculate the distance between the person and the helicopter by using the Pythagorean theorem

$D(t) = \sqrt{h^2 + x^2}$

Lets find the derivative of distance with respect to time

$\frac{dD}{dt} (t) = \frac{2h \cdot \frac{dh}{dt} +2x \cdot\frac{dx}{dt}} {2\sqrt{h^2 + x^2}}$

Substituting the values of h(t) and x(t) and simplifying we get,

$\frac{dD}{dt}(t) = \frac{50t \cdot \frac{dh}{dt} + 20 \cdot \frac{dx}dt}{2\sqrt{625\cdot t^2 + 100 \cdot t^2}}$

$\frac{dh}{dt} = 25ft/sec$

$\frac{dx}{dt} = 10 ft/sec$

$\frac{Dd}{dt} (t) = \frac{1250t +200t}{2\sqrt{725}t}$ = $\frac{725}{\sqrt{725}}$ = $\sqrt{725}$ ft / sec

5 0

3 years ago

If Fg=mg solve for g

Bas_tet [7]

Answer:Fg = mg however newtons second law states that the net force acting on an object is equal to it's mass times it's acceleration so what allows us to say that Fg = mg because certainly not for every single situation the net force is going to equal to the force of gravity please explain... what allows us to say Fg = mg

Source https://www.physicsforums.com/threads/fg-mg-questioned.336776/

Explanation:

6 0

3 years ago

Which of the following was not a factor that got the public interested in NASA? A. real people B. scientific reports C. adventur

fomenos

B. Scientific reports

8 0

3 years ago

Read 2 more answers

What is current electricity? write down its use in our daily like .

Karolina [17]

Answer: Current electricity is a form of electricity in which charges constantly flow. Current electricity is dynamic while static electricity, as the name suggests, is static. How does current electricity work? The steady flow of electrons is termed as current electricity. Uses of Electricity in Household Starting from toaster to refrigerator, microwave, washing machine, dishwasher, electrical chimney, and many more appliances which are simple to use and made for the convenience of day to day activities use electricity to function.

8 0

3 years ago