Dark matter is missing stars that have fallen from the sky. true or false

A train is moving in a straight railway where it covered one third of the distance with

Alexxandr [17]

Answer:

The average speed of the train is 45 km/h

Explanation:

Speed

It's defined as the distance (d) per unit of time (t) traveled by an object. The formula is:

$\displaystyle v=\frac{d}{t}$

Let's call x the total distance covered by the train. It covered d1=1/3x with a speed of v1=25 km/h. The time taken is calculated solving for t:

$\displaystyle t_1=\frac{d_1}{v_1}$

$\displaystyle t_1=\frac{1/3x}{25}$

$\displaystyle t_1=\frac{x}{75}$

Now the rest of the distance:

d2 = x - 1/3x = 2/3x

Was covered at v2=75 km/h. Thus the time taken is:

$\displaystyle t_2=\frac{d_2}{v_2}$

$\displaystyle t_2=\frac{2/3x}{75}$

$\displaystyle t_2=\frac{2x}{225}$

The total time is:

$\displaystyle t_t=\frac{x}{75}+\frac{2x}{225}$

$\displaystyle t_t=\frac{3x}{225}+\frac{2x}{225}$

$\displaystyle t_t=\frac{5x}{225}$

Simplifying:

$\displaystyle t_t=\frac{x}{45}$

The average speed is the total distance divided by the total time:

$\displaystyle \bar v=\frac{x}{\frac{x}{45}}$

Simplifying:

$\boxed{\displaystyle \bar v=45\ km/h}$

The average speed of the train is 45 km/h

5 0

3 years ago

A graph of the net force F exerted on an object as a function of x position is shown for the object of mass M as it travels a ho

saul85 [17]

The change in kinetic energy is $\Delta K = 3Fd$

Explanation:

According to the work-energy theorem, the work done on an object is equal to the change in kinetic energy of the object. Mathematically:

$W=K_f -K_i= \Delta K$

where :

W is the work done on the object

$K_f$ is the final kinetic energy of the object

$K_i$ is the initial kinetic energy

Also, the work done on an object is (assuming that the force is applied parallel to the motion of the object):

$W=F\Delta x$

where

F is the magnitude of the force

$\Delta x$ is the displacement of the object

In this problem, the force acting on the object is

F

While the displacement is the horizontal distance travelled, so

$\Delta x = 3d$

Therefore, the work done is

$W=(F)(3d)=3Fd$

And so the change in kinetic energy is

$\Delta K = 3Fd$

Learn more about work and kinetic energy:

brainly.com/question/6763771

brainly.com/question/6443626

brainly.com/question/6536722

#LearnwithBrainly

5 0

2 years ago

Can someone please help me! BRAINLIEST ANSWER! What happens after the Gulf Stream travels north?

Irina-Kira [14]

A should be the answer since it makes the water down there cold and the air also. (asked my grandma haha

3 0

3 years ago

According to perception of movement, in order to sense movement, humans need to see an object _____.

lesya692 [45]

Answer: The correct answer for the blank is- a. change its position relative to other objects.

Perception of motion can be described as a phenomenon of inferring the direction and speed and of objects, which are moving in a visual scene.

An object is said to be in motion if its position is changed with respect to objects that are present in its surrounding.

Thus, in order to sense motion of objects, humans beings are required to see an object change its position with respect to other objects.

8 0

3 years ago

What is the amount of electric current passing through the heating oil of a hot plate if 25 C of charge passes through it in 7 s

coldgirl [10]

Answer:

Current, I = 3.57A

Explanation:

A current of I amperes means that I Coulombs of charge flows through the conductor (heating coil) per second.

Therefore, in time t, the total charge (Q) passing through any point in which the current (C) flows will be given by the equation;

Q = It

Where; Q is the charge in coulombs; I is the current in amperes; t is the time in seconds.

From the question, we were given the following parameters;

Q = 25C, t= 7secs and I =?

From the equation, Q = It

We make current, I the subject of formula;

Thus, I = Q/t

Substituting into the equation;

I = 25/7

I = 3.57Amp.

3 0

3 years ago