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3 years ago

What is the shortest possible time for a sprinter moving at 4 m/s to finish a 100 meter race?

Physics

1 answer:

Ymorist [56]3 years ago

5 0

The time needed is 25 s

Explanation:

Assuming that the sprinter is moving by uniform motion, then we can use the following equation that relates distance, time and speed:

$v=\frac{d}{t}$

where

v is the speed of the sprinter

d is the distance covered

t is the time elapsed

In this problem, we know that

v = 4 m/s is the speed of the sprinter

d = 100 m is the distance that must be covered

Solving for t, we find the minimum time needed:

$t=\frac{d}{v}=\frac{100}{4}=25 s$

Learn more about speed:

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On a part-time job, you are asked to bring a cylindrical iron rod of density 7800 kg/m3 , length 92.6 cm and diameter 2.95 cm fr

slavikrds [6]

Answer:

48.4293354946 N

Yes

Explanation:

d = Diameter of rod = 2.95 cm

h = Length of rod = 92.6 cm

$\rho$ = Density of rod = 7800 kg/m³

g = Acceleration due to gravity = 9.81 m/s²

Volume of rod

$V=\dfrac{1}{4}\pi d^2h\\\Rightarrow V=\dfrac{1}{4}\times \pi\times (2.95\times 10^{-2})^2\times 92.6\times 10^{-2}$

Mass is given by

$m=\rho V\\\Rightarrow m=7800\times \dfrac{1}{4}\times \pi\times (2.95\times 10^{-2})^2\times 92.6\times 10^{-2}\\\Rightarrow m=4.93673144695\ kg$

Weight is given by

$W=mg\\\Rightarrow W=4.93673144695\times 9.81\\\Rightarrow W=48.4293354946\ N$

The weight of the rod is 48.4293354946 N

The mass of the rod is 4.93673144695 kg which is light. So, I will be able to carry the rod without a cart.

7 0

3 years ago

21. True or false: During heat transfer heat always travels from the warmer object to the cooler object.

guajiro [1.7K]

Answer: True

When 2 things are at different temperatures and they touch eachother, the heat flows from the warmer object to the cooler one.

4 0

3 years ago

One of two 25-year-old identical twins begins a trip on a spaceship traveling at 0.8 c while her twin remains on Earth. The twin

borishaifa [10]

Answer:

This equation is based on twin paradox - a phenomena where one of the twin travels to space at a speed close to speed of light and the other remains on earth. the twin from the space on return discovers that the one on earth age faster.

Solution:

$t_{o}$ = 10 years

v = 0.8c

c = speed of light in vacuum

The problem can be solved by time dilation equation:

$t = \frac{t_{o}}{\sqrt{1 - \frac{v^{2}}{c^{2}}}}$ (1)

where,

t = time observed from a different inertial frame

Now, using eqn (1), we get:

$t = \frac{10}{\sqrt{1 - \frac{(0.8c)^{2}}{c^{2}}}}$

t = 16.67 years

The age of the twin on spaceship according to the one on earth = 25+16.67 =41.66 years

8 0

3 years ago

A cup of water is warmed from 21 °C to 85 °C. What is the difference between these two temperatures, in kelvins?

Ilya [14]

Answer:

337k

Explanation:

First, let us find the difference between the given two temperatures.

Difference = 85°C - 21°C

= 64°C

And now we have to write the temperature in kelvins.

To convert Celcius to Kelvins you can add 273 to the temperature in Celcius.

Let us find it now.

64°C + 273 = 337k

Therefore,

64°C ⇒ 337k

8 0

2 years ago

Why plate tectonics is a scientific theory and not a scientific law.

ser-zykov [4K]

Answer:

We have not drilled to the center of the earth.

Explanation:

7 0

3 years ago