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victus00 [196]
3 years ago
14

Tourists covered 255 km for a 4-hour ride by car and a 7-hour ride by train. what is the speed of the train, if it is 5 km/h gre

ater than the speed of the car?
Physics
1 answer:
LekaFEV [45]3 years ago
4 0
The distance covered by car is equal to (assuming it is moving by uniform motion) the product between the car's speed and the time of the car ride, 4 h:
S_c = v_c t_c
where
v_c is the car's speed
t_c = 4 h is the duration of the car ride

Similarly, the distance covered by train is equal to the product between the train's speed and the duration of the train ride, 7 h:
S_t = v_t t_t

The total distance covered is S=255 km, which is the sum of the distances covered by car and train:
S=255 km = S_c + S_t
which becomes
255 = 4 v_c + 7 v_t (1)
we also know that the train speed is 5 km/h greater than the car's speed:
v_t = 5 + v_c (2)

If we put (2) into (1), we find
255 = 4v_c + 7(5+v_c)
and if we solve it, we find
v_c = 20 km/h
v_t = 25 km/h

So, the car speed is 20 km/h and the train speed is 25 km/h.

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krok68 [10]

An irrational number is a real number that cannot be written as a simple fraction.

4 = 4/1 = rational

0 = 0/1 = rational

-2/3 = rational

4.11111 = irrational

2 = 2/1 = rational

π = 3.141592... = irrational

√6= irrational

Answer:

4.1111, π , √6

3 0
1 year ago
A short 6061-T6 aluminum cylindrical block, having an original diameter of 20mm and a length of 75mm, is placed in a compression
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Explanation:

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5 0
3 years ago
A machine
In-s [12.5K]

Answer:

Power_input = 85.71 [W]

Explanation:

To be able to solve this problem we must first find the work done. Work is defined as the product of force by distance.

W = F*d

where:

W = work [J] (units of Joules)

F = force [N] (units of Newton)

d = distance [m]

We need to bear in mind that the force can be calculated by multiplying the mass by the gravity acceleration.

Now replacing:

W = (80*10)*3\\W = 2400 [J]

Power is defined as the work done over a certain time. In this way by means of the following formula, we can calculate the required power.

P=\frac{W}{t}

where:

P = power [W] (units of watts)

W = work [J]

t = time = 40 [s]

P = 2400/40\\P = 60 [W]

The calculated power is the required power. Now as we have the efficiency of the machine, we can calculate the power that is introduced, to be able to do that work.

Effic=0.7\\Effic=P_{required}/P_{introduced}\\P_{introduced}=60/0.7\\P_{introduced}=85.71[W]

3 0
3 years ago
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Answer:

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6 0
2 years ago
Which phrase best describes sir isaac newton's contributions to modern science and therefore to the industrial revolution?
astraxan [27]
Can you please give the phrases? 

But, I'll help what I can.

First, he was the first to discover gravity. He was not bonked by the head by an apple, rather he watched an apple fall from a tree before he decided to explore gravity further. 

He was also the first scientist to be knighted, which is a great honor, as you can expect. 

Newton also developed The Three Laws of Motion. They are extremely important to physics and are considered some of the foundation for physics today. 

He also discovered calculus, which is complex math that is very helpful to scientists today. 

He also discovered the color spectrum using a glass prism, a dark room and window shade with a hole in it. He was able to project the color spectrum onto a piece of paper.

Those are the few I can think of now, but hope it helps!


7 0
3 years ago
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