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Digiron [165]
3 years ago
10

Identify the true statement. Choose one:

Physics
1 answer:
beks73 [17]3 years ago
4 0

Answer:

A. Underground coal mining is dangerous because of possible tunnel collapse and possible methane gas explosions.

Explanation:

Dangers of underground coal mining include asphyxiation, methane gas poisoning, tunnel collapse and explosions of methane gas, a highly flammable gas. Methane explosions occur since this gas is a byproduct of coal. This explosion can cause tunnel collapse.

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The value of a scientific variable ____. A) can change
gregori [183]
The answer is A: can change
5 0
2 years ago
Read 2 more answers
A delivery truck travels 2.8 km North, 1.0 km East, and 1.6 km South. The final displacement from the origin is ___km to the ___
34kurt

Answer:

The final displacement from the origin is <u>1.6</u> km to the <u>NE</u>

Explanation:

The directions in which the delivery truck travels are;

1) 2.8 km North = 2.8·\hat j, in vector form

2) 1.0 km East = 1.0·\hat i, in vector form

3) 1.6 km South = -1.6·\hat j, in vector form

Therefore, to find the final displacement, Δx, of the delivery truck, we add the individual displacements as follows;

Final displacement, Δd = 2.8·\hat j + 1.0·\hat i +(-1.6·\hat j) = 1.2·\hat j + 1.0·\hat i

Final displacement, = 1.0·\hat i + 1.2·\hat j

Where;

Δx = The displacement in the x-direction = 1.0·\hat i

Δy = The displacement in the y-direction = 1.2·\hat j

The magnitude of the resultant displacement vector is given as follows

\left | d \right | = √((Δx)² + (Δy)²) = √(1² + 1.2²) ≈ 1.6 (To the nearest tenth)

The magnitude of the resultant displacement vector ≈ 1.6 km

The direction of the resultant vector is positive for both the east and north direction, therefore, the direction of the resultant vector = NE

Therefore, the resultant displacement of the delivery truck is approximately 1.6 km, NE from the origin.

3 0
3 years ago
If a car travels 216 kilometers in 4 hours, calculate its speed.
Mariana [72]

Answer:

15 m/s

Explanation:

Speed(m/s) = distance(m)/time(s)

distance = 216 km = 216,000 m

time = 4 hours = 14,400 s

speed = 216000/14400 = 15 m/s

6 0
1 year ago
Read 2 more answers
When a piece of copper is taken to the moon , a change will be observed in it's ?​
SpyIntel [72]
Weight. Because there is less gravity on the moon.
3 0
2 years ago
A 3.8 kg object is lifted 12 meters. approximately how much work is performed during the lifting.
Dmitry [639]

work done=446.9 J . so option (c) is correct.

Explanation:

the formula for work done is given by

W= F d

F= force= mg where m= mass and g= acceleration due to gravity

F= 3.8 (9.8)=37.24 J

so W=37.24 (12)

W=446.9 J

7 0
2 years ago
Read 2 more answers
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