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sammy [17]
3 years ago
14

Dave runs a 400 m race with a speed of 4 m/s. What time will it take him to finish the race?

Physics
1 answer:
tangare [24]3 years ago
5 0

Answer:

The answer should be 100 if not try 200

Explanation:

d=v x t

400m=4m/s x t

/4           /4

100=t

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A car moves in a straight line at 22.0 m/s for 10.0miles, then at 30.0 m/s for another 10.0miles. Calculate the car’s average sp
maw [93]

Answer: 25.38 m/s

Explanation:

We have a straight line where the car travels a total distance D, which is divided into two segments d=10 miles:

D=d+d=2d (1)

Where d=10mi \frac{1609.34 m}{1 mi}=16093.4 m

On the other hand, we know speed is defined as:

S=\frac{d}{t} (2)

Where t is the time, which can be isolated from (2):

t=\frac{d}{S} (3)

Now, for the first segment d=16093.4 m the car has a speed S_{1}=22m/s, using equation (3):

t_{1}=\frac{d}{S_{1}} (4)

t_{1}=\frac{16093.4 m}{22m/s} (5)

t_{1}=731.518 s (6) This is the time it takes to travel the first segment

For the second segment d=16093.4 m the car has a speed S_{1}=30m/s,  hence:

t_{2}=\frac{d}{S_{2}} (7)

t_{2}=\frac{16093.4 m}{30m/s} (8)

t_{2}=536.44 s (9) This is the time it takes to travel the secons segment

Having these values we can calculate the car's average speed S_{ave}:

S_{ave}=\frac{d + d}{t_{1} + t_{2}}=\frac{2d}{t_{1} + t_{2}} (10)

S_{ave}=\frac{2(16093.4 m)}{731.518 s +536.44 s} (11)

Finally:

S_{ave}=25.38 m/s

3 0
3 years ago
In the rectangle to the left, if
Margarita [4]

perimeter of a rectangle = 2(L+B)

90=2(L+B)

90/2=L+B

45=L+B

7 0
3 years ago
When reaching a boundary between two media (1 and 2), an incident ray is partially reflected and partially refracted. The ray is
podryga [215]

Answer: critical angle, sin^-1 (n2/n1)

Explanation: the angle of incidence at which the retracted ray makes an angle of 90° with the normal is known as the critical angle.

Snell's law defined refraction mathematically as shown below

n1 sin θi = n2 sin θr

n1 = refractive index of the first medium

n2 = refractive index of the second medium

θi = angle of incidence

θr = angle of refraction

When the refrafted ray is perpendicular to the normal, the angle of refraction (θr) is 90° hence making the angle of incidence (θi) the critical angle θc

By substituting these conditions into the Snell's law, we have that

n1 sin θc = n2 sin 90

According to trigonometry, the value of sin 90 is 1, hence we have that

n1 sin θc =n2

sin θc = n2/n1

θc = sin^-1 (n2/n1)

3 0
2 years ago
Find the difference in temperature between the water at the top and the bottom of a waterfall 100 m high.
Alekssandra [29.7K]
The answer would be 60 cuz a watetfall is a waterfall

7 0
3 years ago
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Who is the richest artist in the Gambia 2020​
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Answer:

Jaliba Kuyateh is the most famous and wealthiest Gambian musician.

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