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MAVERICK [17]
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.
Physics
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
Kinematics
leonid [27]

Answer:

a)

a = 2 [m/s^2]

b)

a = 1.6 [m/s^2]

c)

xt = 2100 [m]

Explanation:

In order to solve this problem we must use kinematics equations. But first we must identify what kind of movement is being studied.

a)

When the car moves from rest to 40 [m/s] by 20 [s], it has a uniformly accelerated movement, in this way we can calculate the acceleration by means of the following equation:

v_{f} = v_{i}+(a*t)

where:

Vf = final velocity = 40 [m/s]

Vi = initial velocity = 0 (starting from rest)

a = acceleration [m/s^2]

t = time = 20 [s]

40 = 0 + (a*20)

a = 2 [m/s^2]

The distance can be calculates as follows:

v_{f} ^{2} =  v_{i} ^{2}+(2*a*x)

where:

x1 = distance [m]

40^2 = 0 + (2*2*x1)

x1 = 400 [m]

Now the car maintains its speed of 40 [m/s] for 30 seconds, we must calculate the distance x2 by means of the following equation, it is important to emphasize that this movement is at a constant speed.

v = x2/t2

where:

x2 = distance [m]

t2 = 30 [s]

x2 = 40*30

x2 = 1200 [m]

b)

Immediately after a change of speed occurs, such that the previous final speed becomes the initial speed, the new Final speed corresponds to zero, since the car stops completely.

v_{f} = v_{i}-a*t

Note: the negative sign of the equation means that the car is stopping, i.e. slowing down.

0 = 40 - (a *25)

a = 40/25

a = 1.6 [m/s^2]

The distance can be calculates as follows:

v_{f} ^{2}  = v_{i} ^{2} -2*a*x3\\

0 = (40^2) - (2*1.6*x3)

x3 = 500 [m]

c)

Now we sum all the distances calculated:

xt = x1 + x2 + x3

xt = 400 + 1200 + 500

xt = 2100 [m]

8 0
2 years ago
Why is atomaspheric pressure greater at the surface on Earth
andrew-mc [135]
Hello!

Because as you get closer to the surface of the earth, the more air that is on top of you. At the top of the atmosphere, there is less air, and everything is a vacuum, where you have no weight. When you get close to the earth, the weight of the air builds until it when you're at the very lowest point of the earths surface, all the air in the atmosphere above you is pressing down.

Thank You!


5 0
3 years ago
Read 2 more answers
A golf ball is released from rest from the top of a very tall building. Choose a coordinate system whose origin is at the starti
Zigmanuir [339]

Answer:

Velocity of the ball after 3.04 (s) = 29.79 (m/s)

Explanation:

From the free fall movement we have the following formulas: Vf^{2} = Vo^{2} - 2gh and h=Vo*t - \frac{g*t^{2} }{2}, First we need to find the height to time iqual to 3.04 s using the formula: h=Vo*t - \frac{g*t^{2} }{2} and remember that golf ball was released from the rest (Vo= 0 (m/s)) so h= (0 (m/s))*(3.04 (s)) - \frac{9.8 (m/s^2)*(3.04 (s))^{2} }{2}, we get: h = -45.28 (m) with the height that we have got, now the velocity of the ball is calculate using Vf^{2} = Vo^{2} - 2gh solving for Vf, we get: Vf = \sqrt{Vo^{2}-2*g*h } replacing the values given Vf = \sqrt{(0 m/s)^{2}-2*(9.8 m/s^2)*(-45.28 m) }, so we get: Vf = 29.79 (m/s).

5 0
3 years ago
Read 2 more answers
3. How does the mass of a proton compare to the mass of an electron?
o-na [289]

Answer:

Proton, stable subatomic particle that has a positive charge equal in magnitude to a unit of electron charge and a rest mass of 1.67262 × 10−27 kg, which is 1,836 times the mass of an electron.

7 0
3 years ago
Compute the kinetic energy of a proton (mass 1.67×10−27kg ) using both the nonrelativistic and relativistic expressions for spee
JulsSmile [24]

Answer:

The non-relativistic kinetic energy of a proton is 6.76\times10^{-12}\ J

The relativistic kinetic energy of a proton is 7.25\times10^{-12}\ m/s

Explanation:

Given that,

Mass of proton m=1.67\times10^{-27}\ kg

Speed v= 9.00\times10^{7}\ m/s

We need to calculate the kinetic energy for non relativistic

Using formula of kinetic energy

K.E=\dfrac{1}{2}mv^2

Put the value into the formula

K.E=\dfrac{1}{2}\times1.67\times10^{-27}\times(9.00\times10^{7})^2

K.E=6.76\times10^{-12}\ J

We need to calculate the kinetic energy for relativistic

Using formula of kinetic energy

K.E=mc^2(\sqrt{(\dfrac{1}{1-\dfrac{v^2}{c^2}})}-1)

K.E=1.67\times10^{-27}\times(3\times10^{8})^{2}\cdot\left(\sqrt{\frac{1}{1-\frac{\left(9.00\times10^{7}\right)^{2}}{(3\times10^{8})^{2}}}}-1\right)

K.E=7.25\times10^{-12}\ m/s

Hence, The non-relativistic kinetic energy of a proton is 6.76\times10^{-12}\ J

The relativistic kinetic energy of a proton is 7.25\times10^{-12}\ m/s

7 0
3 years ago
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