Ask question

Ask question

All categories

2 years ago

8

In the 2008 Olympics, Jamaican sprinter usain's bolt average shocked the world as he ran the 100- meter dash in 9.69 seconds. De

termine usain's average speed for the race.

1 answer:

torisob [31]2 years ago

6 0

<span>Avg Speed = Total Distance/Total time taken avg speed= 100 m / 9.69sec = 10.3 m/sec.</span>

You might be interested in

What are the SI units for distance and time?

Anton [14]

Answer:

distance is meters, time is seconds

8 0

3 years ago

Read 2 more answers

A 39-foot ladder is leaning against a vertical wall. If the bottom of the ladder is being pulled away from the wall at the rate

Viefleur [7K]

Answer:

The rate of change of the area when the bottom of the ladder (denoted by $b$ ) is at 36 ft. from the wall is the following:

$\frac{dA}{dt}|_{b=36}=-571.2\, ft^2/s$

Explanation:

The Area of the triangle is given by $A=h\times b$ where $h=\sqrt{l^2-b^2}$ (by using the Pythagoras' Theorem) and $b$ is the length of the base of the triangle or the distance between the bottom of the ladder and the wall.

The area is then

$A=\sqrt{l^2-b^2}b$

The rate of change of the area is given by its time derivative

$\frac{dA}{dt}=\frac{d}{dt}\left(\sqrt{l^2-b^2}\cdot b\right)$

$\implies \frac{dA}{dt}=\frac{d}{dt}\left(\sqrt{l^2-b^2}\right)\cdot b+\frac{db}{dt}\cdot\sqrt{l^2-b^2}$

$\implies\frac{dA}{dt}=\frac{1}{2\sqrt{l^2-b^2}}\frac{d}{dt}(l^2-b^2)\cdot b+\sqrt{l^2-b^2}}\cdot \frac{db}{dt}$ Product rule

$\implies\frac{dA}{dt}=-\frac{1}{2\sqrt{l^2-b^2}}\cdot 2\cdot b^2\cdot \frac{db}{dt}+\sqrt{l^2-b^2}}\cdot \frac{db}{dt}$ Chain rule

$\implies\frac{dA}{dt}=-\frac{1}{\sqrt{l^2-b^2}}\cdot b^2\cdot \frac{db}{dt}+\sqrt{l^2-b^2}}\cdot \frac{db}{dt}$

$\implies\frac{dA}{dt}=\frac{db}{dt}\left(-\frac{1}{\sqrt{l^2-b^2}}\cdot b^2+\sqrt{l^2-b^2}}\right)$

In here we can identify $b=36\, ft$ , $l=39$ and $\frac{db}{dt}=8\,ft/s$ .

The result is then

$\frac{dA}{dt}=8\left(-\frac{1}{\sqrt{39^2-36^2}}\cdot 36^2+\sqrt{39^2-36^2}}\right)=-571.2\, ft^2/s$

3 0

2 years ago

Tell whether each element has a high or low electronegativity : bromine, chlorine, potassium, lithium

finlep [7]

Answer:

Bromine-2.8 high

Chlorine-3.0 high

Potassium-0.8 low

Lithium-1.0 low

Explanation:

3 0

3 years ago

What is the difference between collinear and coplanar

DIA [1.3K]

Answer:

Collinear is when points are in the same straight line but coplanar is when points are all on the same plane.

4 0

3 years ago

If you push on a wall with a force of 200 N, with what force does the wall push back?

PSYCHO15rus [73]

200 N, that is if the force is balanced and the wall doesn't move

8 0

2 years ago