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3 years ago

14

A subway goes 5 km from the sports complex to downtown in 30 minutes. What is the average speed of the subway? A. 2.5 km/h B. 6

km/h C. 10 km/h D. 150 km/h

2 answers:

rusak2 [61]3 years ago

8 0

It should be B!!!! Because you are suppose divide30km by 5 which is 6km/h.

VashaNatasha [74]3 years ago

4 0

Answer:

C. 10 km/h

Explanation:

IN order to calculate the average speed of a train that goes 5 km from the sports complex to downtown you just need to use the formula for speed:

$speed=\frac{distance}{time}$

Now you have to remember that you have time in minutes, and that in your options you have hours, so you need to convert minutes to hours:

$\frac{60 minutes}{1 hour}= \frac{30 minutes}{x} \\x=\frac{30minutes*1 hour}{60 minutes} \\x=.5 hours$

Now that you have the time in hours you just insert the values into the first formula:

$speed=\frac{distance}{time}\\speed=\frac{5km}{.5 hours} \\speed=15 \frac{km}{h}$

Your answer is 10 kilometers per hour.

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Flowchart symbols

MArishka [77]

Answer:

Option (A)

Explanation:

A flowchart can be described as a representation of a process or an algorithm in a sequential manner (stepwise) in the form of diagrams. These steps are made of symbols that are connected to one another with the help of arrows. These arrows are used to show the direction of the process.

There are mainly four symbols that are used to describe a flow chart, which includes-

Oval or Pill Shape- This type of symbol is used to depict the start or the end of a process.

Rectangle Shape- This type of symbols is used to describe the process .

Diamond Shape- This type of symbol is used to represent decision s.

Parallelogram- This type of symbol is used for the representation of an input or an output.

Thus, the correct answer is option (A).

5 0

3 years ago

Volume of an block is 5 cm3. If the density of the block is 250 g/cm3, what is the mass of the block ?

wlad13 [49]

Answer:

The mass of the block is 1250g.

Explanation:

Given that the formula for density is ρ = mass/volume. Then you have to substitute the values into the formula :

$ρ = \frac{mass}{volume}$

Let density = 250,

Let volume = 5,

$250 = \frac{m}{5}$

$m = 250 \times 5$

$m = 1250g$

7 0

3 years ago

The speed of an object changes only when it is acted on by an unbalanced force.

Nikitich [7]

Answer:

If an object has a net force acting on it, it will accelerate. The object will speed up, slow down or change direction. An unbalanced force (net force) acting on an object changes its speed and/or direction of motion. An unbalanced force is an unopposed force that causes a change in motion.

Explanation:

I hope this helps you out and if your feeling generous plz mark brainliest it helps me a lot thank you:)

6 0

3 years ago

Technician A says when diagnosing an overheating hydraulic system, be sure that the oil cooler is not plugged and the cooler’s f

mel-nik [20]

Answer:

Tech B is correct and Tech A is incorrect.

Explanation:

Here Tech A is wrong because when diagnosing an overheating hydraulic system, it is not necessary to un plugg the oil cooler rather it should be plugged to for proper diagnosis.

Technician B says running the hydraulic system at a lower operating temperature will reduce the possibly of oil oxidation is correct statement because at temperature oil's physical as well as chemical property tend to change.

Hence, Tech B is correct and Tech A is incorrect.

8 0

3 years ago

A 50 kg runner runs up a flight of stairs. The runner starts out covering 3 steps every second. At the end the runner stops. Thi

nadezda [96]

To solve the problem it is necessary to take into account the concepts of kinematic equations of motion and the work done by a body.

In the case of work, we know that it is defined by,

$W = F * d$

Where,

F= Force

d = Distance

The distance in this case is a composition between number of steps and the height. Then,

$d=h*N$ , for h as the height of each step and N number of steps.

On the other hand we have the speed changes, depending on the displacement and acceleration (omitting time)

$V_f^2-V_i^2 = 2a\Delta X$

Where,

$V_f =$ Final velocity

$V_i =$ Initial Velocity

a = Acceleration

$\Delta X =$ Displacement

PART A) For the particular case of work we know then that,

$W = F*d$

$W = m*g*(h*N)$

$W = 50*9.8*(0.3*30)$

$W = 4.41kJ$

Therefore the Work to do that activity is 4.41kJ

PART B) To find the acceleration (from which we can later find the time) we start from the previously given equation,

$V_f^2-V_i^2 = 2a\Delta X$

Here,

$V_i = \frac{0.3*3}{1} = 0.90m/s\rightarrow$ 3 steps in one second

$v_f = 0$

Replacing,

$V_f^2-V_i^2 = 2a\Delta X$

$0-0.9^2=2a(30*0.3)$

Re-arrange for a,

$a = -\frac{0.9^2}{2*30*0.3}$

$a = -45*10^{-3}m/s^2$

At this point we can calculate the time, which is,

$t = \frac{\Delta V}{a}$

$t = \frac{0-0.9}{-45*10^{-3}}$

$t = 20s$

With time and work we can finally calculate the power

P = \frac{W}{t} = \frac{4.41}{20}

P = 0.2205kW

6 0

4 years ago