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3 years ago

A 3.5 kg book is sitting at rest on a table. what is the value of the normal force being exerted by the table on the book?

Physics

1 answer:

Ira Lisetskai [31]3 years ago

6 0

This is 3.5 * 9.8 (where 9.8 ms-2 is the acceleration due to gravity).

= 34.3 Newtons ( answer).

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Careful measurements have been made of Olympic sprinters in the 100-meter dash. A quite realistic model is that the sprinter's v

mihalych1998 [28]

Answer:

$\displaystyle a(0 )=8.133\ m/s^2$

$\displaystyle a(2)=2.05\ m/s^2$

$\displaystyle a(4)=0.52\ m/s^2$

b. $\displaystyle X(t)=11.81(t+1.45\ e^{-0.6887t})-17.15$

c. $t=9.9 \ sec$

Explanation:

Modeling With Functions

Careful measurements have produced a model of one sprinter's velocity at a given t, and it's is given by

$\displaystyle V(t)=a(1-e^{bt})$

For Carl Lewis's run at the 1987 World Championships, the values of a and b are

$\displaystyle a=11.81\ ,\ b=-0.6887$

Please note we changed the value of b to negative to make the model have sense. Thus, the equation for the velocity is

$\displaystyle V(t)=11.81(1-e^{-0.6887t})$

a. What was Lewis's acceleration at t = 0 s, 2.00 s, and 4.00 s?

To compute the accelerations, we must find the function for a as the derivative of v

$\displaystyle a(t)=\frac{dv}{dt}=11.81(0.6887\ e^{0.6887t})$

$\displaystyle a(t)=8.133547\ e^{-0.6887t}$

For t=0

$\displaystyle a(0)=8.133547\ e^o$

$\displaystyle a(0 )=8.133\ m/s^2$

For t=2

$\displaystyle a(2)=8.133547\ e^{-0.6887\times 2}$

$\displaystyle a(2)=2.05\ m/s^2$

$\displaystyle a(4)=8.133547\ e^{-0.6887\times 4}$

$\displaystyle a(4)=0.52\ m/s^2$

b. Find an expression for the distance traveled at time t.

The distance is the integral of the velocity, thus

$\displaystyle X(t)=\int v(t)dt \int 11.81(1-e^{-0.6887t})dt=11.81(t+\frac{e^{-0.6887t}}{0.6887})+C$

$\displaystyle X(t)=11.81(t+1.45201\ e^{-0.6887t})+C$

To find the value of C, we set X(0)=0, the sprinter starts from the origin of coordinates

$\displaystyle x(0)=0=>11.81\times1.45201+C=0$

Solving for C

$\displaystyle c=-17.1482\approx -17.15$

Now we complete the equation for the distance

$\displaystyle X(t)=11.81(t+1.45\ e^{-0.6887t})-17.15$

c. Find the time Lewis needed to sprint 100.0 m.

The equation for the distance cannot be solved by algebraic procedures, but we can use approximations until we find a close value.

We are required to find the time at which the distance is 100 m, thus

$\displaystyle X(t)=100=>11.81(t+1.45\ e^{-0.6887t})-17.15=100$

Rearranging

$\displaystyle t+1.45\ e^{-0.6887t}=9.92$

We define an auxiliary function f(t) to help us find the value of t.

$\displaystyle f(t)=t+1.45\ e^{-0.687t}-9.92$

Let's try for t=9 sec

$\displaystyle f(9)=9+1.45\ e^{-0.687\times 9}-9.92=-0.92$

Now with t=9.9 sec

$\displaystyle f(9.9)=9.9+1.45\ e^{-0.687\times 9.9}-9.92=-0.0184$

That was a real close guess. One more to be sure for t=10 sec

$\displaystyle f(10)=10+1.45\ e^{-0.687\times 10}-9.92=0.081$

The change of sign tells us we are close enough to the solution. We choose the time that produces a smaller magnitude for f(t).

$At t\approx 9.9\ sec, \text{ Lewis sprinted 100 m}$

7 0

3 years ago

What's true about the elliptical path that the planets follow around the sun?

sattari [20]

Answer:

well, it is not a solid path and thats a teeny tiny fact

5 0

1 year ago

Find the electron and hole mobilities, and the resistivity of intrinsic silicon at 300K. Is intrinsic silicon a semiconductor

tino4ka555 [31]

Answer:

Resistivity = 231.481 K Ohm

Yes, Intrinsic Silicon is the semiconductor.

Explanation:

Solution:

At 300K:

Let suppose mobility of electron in intrinsic semiconductor = $M_{e}$

Mobility of electron in intrinsic semiconductor is:

$M_{e}$ = 1300 $cm^{2}$ /volt.sec

Let suppose mobility of hole in intrinsic semiconductor = $M_{h}$

$M_{h}$ = 500 $cm^{2}$ /volt.sec

We know that, intrinsic silicon semiconductor has equal number of holes and electrons. So,

At 300 K

Intrinsic Carrier Concentration = 1.5 x $10^{10}$ / $cm^{3}$ = C

And,

Conductivity of intrinsic Silicon is:

σ = C x ( $M_{h}$ + $M_{e}$ ) e

e = 1.6 x $10^{-19}$ C

So, plugging in the values, we get:

σ = C x ( $M_{h}$ + $M_{e}$ ) e

σ = 1.5 x $10^{10}$ x (500 + 1300) x 1.6 x $10^{-19}$

σ = 4.32 x $10^{-6}$

So, now we can find the resistivity.

Resistivity = 1/σ

Resistivity = 1/ 4.32 x $10^{-6}$

Resistivity = 231.481 K Ohm

Yes, Intrinsic Silicon is the semiconductor.

7 0

2 years ago

What is one latitude where there is no continental barriers?

AveGali [126]

The equator has no continental borders.

5 0

3 years ago

Read 2 more answers

Can someone answer these questions

Aleks04 [339]

Answer:

1. Following the recoil principle, rockets use combustion (a controlled explosion) to work against earth's gravitational attraction.

2. A force is a push or a pull that acts upon an object as a results of its interaction with another object. ... These two forces are called action and reaction forces and are the subject of Newton's third law of motion. Formally stated, Newton's third law is: For every action, there is an equal and opposite reaction.

(via physicsclassroom.com)

3. The combustion throws out material with very high momentum and is, physically speaking, the action. In reaction to that that, the rocket moves away from it (upward when in starts and has the action underneath it)

4. To show the world that commercial manned space missions are safely possible. Some may also like the fact that the US can now do, or rather order, manned flights into space without the help of the russian space agency (Roskosmos).

5. Robert Behnken and Douglas Hurley

6. The international space station (ISS)

7. Yes, Stage 1 of the rocket landed on the drone ship. The crew opened the hatch to enter the space station after 21 hours and 39 minutes after the launch from Cape Canaveral.

8. To have private contractors such as SpaceX actively in the field, there are now more interest groups that participate in space travel. And they can interact with other companies as well.

Also, due to Musks dream and efforts of SpaceX, space travel seems to get a lot cheaper.

That might indeed open the way back to the moon and further to the Mars for human space flight.

Governments such as the US planned on such things for decades, but changed plans ever since, and routinely changed leadership and the opinion on what's important.

Now Spaceflights can become less politically motivated and more commercially. That seems to be a more stable way over long periods of time.

(wrote most of it for you myself, even tough I'm not a native English speaker. would really appreciate the brainliest if you appreciate the work)

5 0

2 years ago

Read 2 more answers