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Charra [1.4K]
3 years ago
11

A train travels 98 kilometers in 4 hours, and then 61 kilometers in 3 hours. What is its average speed?

Physics
1 answer:
IrinaK [193]3 years ago
6 0
Speed (velocity)=distance/time

V1=98km/4hr=24.5km/hr
V2=61km/3hr=20.3km/hr

Average speed (velocity)=total velocity/ number

Average speed (velocity)=44.8km/hr/2=22.4

So the average speed is 22.4km/hr
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A person walks first at a constant speed of 5.50 m/s along a straight line from point A to point B and then back along the line
Sav [38]

Answer:

4.25 m/s

Explanation:

They walked the first distance at 5.50 m/s, then the same distance at 3 m/s.

Since the distances are equal, the average speed is simply the average of 5.50 and 3.

(5.50 + 3) / 2 = 4.25

Her average speed over the entire trip is 4.25 m/s.

8 0
3 years ago
The membrane that surrounds a certain type of living cell has a surface area of 4.3 x 10-9 m2 and a thickness of 1.1 x 10-8 m. A
Nadusha1986 [10]

Answer:

The charge resides on the outer surface = 1.245 \times 10^{-12} C

Explanation:

Surface area of cell  (A) = 4.3\times 10^{-9}  m^{2}

Separation between two plate  (d) = 1.1 \times 10^{-8}  m  

Dielectric constant (k) = 4.2

Potential difference (\Delta V) = 85.7 \times 10^{-3} V

The capacitance of parallel plate capacitor in free space is given by,

           C = \frac{\epsilon_{o} A }{d}

Where \epsilon_{o}  = permittivity of free space = 8.85 \times 10^{-12}

The Capacitance of capacitor is increase by k times when it placed in dielectric medium.

C_{dielectric}  = \frac{k \epsilon_{o} A }{d}

And we know that, C = \frac{Q}{ \Delta V}

So charge on the outer surface is given by,

      Q = \frac{k \epsilon A \Delta V }{d}

      Q = \frac{4.2 \times 4.3 \times 10^{-9} \times 8.85 \times 10^{-12} \times 85.7\times 10^{-3}   }{1.1 \times 10^{-8} }

      Q = 1.245 \times 10^{-12}

3 0
3 years ago
Which country had the largest population in 1997
nignag [31]
China i hope this helped
6 0
3 years ago
Lana wanted to do an investigation to see what kind of birdseed the birds in her neighborhood like best. She purchased three of
Misha Larkins [42]

Answer:

The level of seed in each feeder

Explanation:

The independent variable is the variable which is the suspected cause of an observation, it is the variable that produce the effect observed in the dependent variable. The dependent variable is the variable that is measured

The independent variable is normally the x-value while the dependent variable is the y-value

In the question, Lana wants to find out the kind of birdseed that the neighborhood birds like (to eat) the most by feeding them different types of birdseed and measuring the level of the birdseed in the feeders at regular intervals

the independent variable is the bird seed types which Lana gives to the birds, to determine the type of bird seeds the birds like

The dependent variable is the level of the seed in the feeder which depends on the type of seeds the birds like.

3 0
3 years ago
Consider two carts, of masses m and 2m, at rest on an air track. if you first push one cart for 3 s and then the other for the s
Marrrta [24]
F = m₁ a₁ = m₂ a₂

if m₁ = m and m₂ = 2m :

F = ma₁ = 2m  a₂ ⇒ a₁ = 2 a₂
 
since v = at + v₀  with t = 3, v₀ = 0 ⇒ v = 3a:

v₁ = 2 v₂

since p = vm with v₁ = 2v and v₂ = v :

p₁ = v₁m₁ = 2v ⁻ m
p₂ = v₂m₂ = v ⁻ 2m

p₁ = p₂

8 0
3 years ago
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