1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Darina [25.2K]
3 years ago
9

On a 100km track , a train travels the first 30km with a speed of 30km/h . How fast the train travel the next 70 km if the avera

ge speed for the entire journey is 40km/h?
Physics
1 answer:
kenny6666 [7]3 years ago
6 0

Answer:

v = 46.67 km/h

Explanation:

We will use the following formula throughout this numerical:

s = vt

where,

s = distance covered

v = speed

t =  time taken

<u>FOR FIRST 30 km:</u>

s = 30 km

v = 30 km/h

t = t₃₀ = ?

Therefore,

30 km = (30 km/h)(t₃₀)

t₃₀ = (30 km)/(30 km/h)

t₃₀ = 1 h

<u>FOR TOTAL 100 km:</u>

s = 100 km

v = 40 km/h (Average Speed)

t = total time = ?

Therefore,

100 km = (40 km/h)(t)

t = (100 km)/(40 km/h)

t = 2.5 h

<u>FOR LAST 70 km:</u>

s = 70 km

t₇₀ = t - t₃₀ = 2.5 h - 1 h = 1.5 h

v = v₇₀ = ?

Therefore,

70 km = v(1.5 h)

v = 70 km/1.5 h

<u>v = 46.67 km/h</u>

You might be interested in
Explain two ways you could reduce the friction between two surfaces
abruzzese [7]
<span>A lubricant such as oil, grease, graphite powder  can reduce the friction between two surfaces. Or using metal balls to space them and reduce the contact surface area as used in ball bearings.</span>
3 0
3 years ago
A 20-kg boy slides down a smooth, snow-covered hill on a plastic disk. The hill is at a 10° angle to the horizontal, and the slo
zvonat [6]

Answer:

13 m/s

Explanation:

I assume we are ignoring friction.

The boy's PE will all be converted to KE at the bottom of the hill.

to find PE = mgh   we need to know h

   h = 50 sin 10 = 8.68 meters

     then:    PE = 20 * 9.81 * 8.68 =<u> 1703.49</u> j

KE = 1/2 m v^2 = <u>1703 .49</u>

            v = 13 m/s

7 0
2 years ago
Which of the following objects cannot make a shadow? Broken piece of glass from a window/wooden pane of the same window? Explain
Lorico [155]

Answer:

broken pieces of glass from a window can't form a shadow.

Explanation:

the reason is that shadow is formed only when light rays hits an opaque object, which doesn't let light to pass through it, but glass is a transparent object, hence light rays passes through it forming no shadow..

<em>i</em><em> </em><em>hope</em><em> </em><em>it</em><em> </em><em>helped</em><em>.</em><em>.</em><em>.</em><em>.</em>

4 0
3 years ago
True or false? Once the sun explodes, the whole solar system will go with it.
liberstina [14]
True. That is how powerful the sun is. But it will explode in only about 5 billion years.
6 0
3 years ago
1. A toy car is marked to go at 0.5m/s, which of the following sets of
Lostsunrise [7]

Answer:

b. 0.6m/s, 0.7m/s, 0.61m/s, 0.62m/s

Explanation:

Precision of a measurement is the closeness of the experimental values to one another. Hence, experimental measurements are said to be precise if they are close to each other irrespective of how close they are to the accepted value. Precision can be determined by finding the range of each experimental value. The measurement with the LOWEST RANGE represents the MOST PRECISE.

Note: Range is the highest value - lowest value

Set A: 1.5 - 0.8 = 0.7

Set B: 0.7 - 0.6 = 0.1

Set C: 2.4 - 2.0 = 0.4

Set D: 3.1 - 2.9 = 0.2

Set B has the lowest range (0.1), hence, represent the most precise value.

8 0
3 years ago
Other questions:
  • The electric field intensity at a particular location surrounding a Van de Graaff generator is 4.5x103 N/C. Determine the magnit
    5·2 answers
  • Sound waves are actually a form of what kind of energy?
    11·2 answers
  • Why do concave lenses always form virtual images?
    11·2 answers
  • When titanium bonds with oxygen, the ionic compound that forms has the chemical formula Ti2O3 and consists of Ti3+ ions and O2-
    7·1 answer
  • A 64 kg cross-country skier glides over snow. Thecoefficient
    11·1 answer
  • A toy airplane, flying in a horizontal, circular
    5·2 answers
  • On what factors capacitance of parallel plate capacitor depends?
    13·1 answer
  • One of the reasons it is important to keep our water supplies pollution free is potability. Water that is potable is
    8·2 answers
  • Distinguishing Types of Mirrors<br> Light is coming from the left; which is a concave mirror?
    15·1 answer
  • Which famous astronomer discovered jupiter’s largest moons?.
    15·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!