All categories

3 years ago

Help on the second part please (b)

Physics

1 answer:

Oksanka [162]3 years ago

4 0

I'll do that with pleasure. But first, we seriously need to discuss part-A.
The answer to part-A is used to solve part-B, and you don't have it yet.

I loved the way you set up part-A ... started out with the formula you'll use
to solve it, then listed the given information neatly, and substituted the given
information into the formula. All of that was so beautifully laid out ... with
units and everything, which hardly anybody ever does ... that I didn't notice
the absurd result at first.

Angie ! Take two steps back and look over part-A ! You multiplied
(200 and something) by (100 and something), and got an answer of
(200 and something) ! What's up with that ? ! ?

Everything outside the box is correct and beautiful ... units and everything.
Inside the box should be 30,021 kg-m/s .

NOW we're equipped to work on part-B:

You start out with F = m a .
That's the best formula to use for roughly 99.9% of these motion problems ...
but not for this one, sadly.

Here's what you need for part-B. Again, I love the way you start out listing
the formula you're going to use, and all the data you know.
But I think the whole subject of 'Impulse' temporarily slipped your mind.
Here's a quick review:

-- (force) acting for (some limited time) is called "Impulse".
-- The magnitude of impulse is (force) x (time).
-- Impulse is a vector. The direction of impulse is the direction of the force.
-- Look at the units. (I wouldn't do this with anyone else, but you're different ...
you have an understanding and appreciation for units.)

force = 'newton' = kg-m/s²
time = second

Impulse = (force) · (time)

      = (kg-m/s²) · (sec) = kg-m/s . Same units as momentum !

It turns out that the amount of impulse is exactly the amount of
change in momentum !

You push on an object with (some force) for (some time).
Then you stop pushing and you let the object go on its way.
The impulse you delivered to the object is (force) x (time), and that's
exactly how much momentum you gave it !

NOW ... The motorcycle has 30,021 kg-m/s of momentum.
In order to stop it ...
that's how much momentum it needs to lose.
OR
that's how much impulse you have to give it, opposite to its motion.

   (Force) x (time) = 30,021 kg-m/s

Divide each side
by t = 0.05 sec: Force    = (30,021 kg-m/s) / (0.05 sec)

= (30,021 / 0.05) kg-m/s²

=    600,423 newtons

(roughly 135,000 pounds)

(That's why a motorcycle crash
   can often mess up your hair.
   Or worse. )

You might be interested in

An 80 kg astronaut has gone outside his space capsule to do some repair work. Unfortunately, he forgot to lock his safety tether

Anna [14]

Answer:

the time taken by the astronaut to reach safety = 9.8 hr

Explanation:

The equation for intensity can be written as :

$I = \frac{P}{A}$

where :

$\frac{I}{c}= \frac{F}{A}$

Replacing that into the above previous equation; we have:

$\frac{P}{Ac}=\frac{F}{A}$

$F = \frac{P}{c}$

However ; the force needed to push the astronaut is as follows:

F = ma

where ;

m = mass of the astronaut and a = its acceleration

we as well say;

$\frac{P}{c} = ma$

$a = \frac{P}{mc}$

Replacing P with 1000 W ; m with 80 kg and $3*10^{8} \ m/s$ for c

Then; a = $\frac{1000 \ W}{(80)(3.0*10^8)}$

a = $4.2*10^{-8} \ m/s$

It is also known that the battery will run for one hour and after which the battery on the laser will run out

Then to determine the change in the position after the first hour ; we have:

$\Delta x_1 = \frac{1}{2}*4.2*10^{-8} \ m/s^2 ) (1.0 \ h)^2$

$\Delta x_1 = \frac{1}{2}*4.2*10^{-8} \ m/s^2 ) (1.0 *3600 s)^2$

= 0.27 m

Furthermore, the final velocity of the astronaut is determined as:

$v_1 = at_1$

where ;

$v_1 = final \ velocity$

replacing $t_1 = 1.0 \ h$ and a = $4.2*10^{-8} \ m/s$ ; Then:

$v_1 = (4.2*10^8 \ m/s * 1.0 \ h * \frac{ 3600\ s}{1.0 \ h})$

$v_1 = 1.51 *10^{-4} \ m/s$

Also; when he drifted 5.0 m away from the capsule; the distance is far short of the 5 m but he still have 9 hours left of oxygen . In addition to that, he acceleration is also zero and the final velocity remains the same, so:

To find the final distance traveled by the astronaut ;we have:

$\Delta x_2 = d - \Delta x_1$

where;

$\Delta x_2$ = the final distance

d = total distance

So;

$\Delta x_2 = 5 m - 0.27 m \\ \\ \Delta x_2 = 4.73 \ m$

The time taken to reach the final distance can be calculated as:

$t_2 = \frac{\Delta x_2 }{v_1}$

where;

$t_2$ = is the time to reach the final distance

Replacing 4.73 for ${\Delta x_2 }$ and $1.51*10^{-4}$ m/s for $v_1$

$t_2 = \frac{4.73 \ m }{1.51*10^{-4} \ m/s}$

$t_2 = 31500 \ s (\frac{1.0 \ h}{3600 \ s} )$

$t_2 = 8.8 \ h$

We knew the laser was operated for 1 hour; thus the total time taken by the astronaut to reach the final distance is the sum of the time taken to reach the final distance and the operated time of the laser.

Hence ; the time taken by the astronaut to reach safety = 9.8 hr

8 0

3 years ago

A proton is released from rest at the positive plate of a parallelplatecapacitor. It crosses the capacitor and reaches the negat

Triss [41]

Answer:

2.1406 × $10^6$ m/sec

Explanation:

we know that energy is always conserved

so from the law of energy conservation

$qV=\frac{1}{2}mv^2$

here V is the potential difference

we know that mass of proton = 1.67× $10^{-27}$ kg

we have given speed =50000m/sec

so potential difference $V=\frac{\frac{1}{2}\times 1.67\times 10^{-27}50000^2}{1.6\times 10^{-19}}=13.045$

now mass of electron =9.11× $10^{-31}$

so for electron

$\frac{1}{2}\times 9.11\times 10^{-31}v^2=1.6\times 10^{-19}\times 13.045=2.1406\times 10^6 m/sec$

so the velocity of electron will be 2.1406× $10^6$ m/sec

4 0

3 years ago

A 44 kg block lies on a horizontal frictionless surface. A horizontal force of 110 N is applied to the block. (a) Determine the

Oksana_A [137]

44k jkjk know the answer

8 0

3 years ago

Which one of the following types of electromagnetic radiation causes certain substances to fluoresce?

ioda

From the choices given, ultraviolet rays is a type electromagnetic radiation that causes certain substances to fluoresce. It cannot be detected by the naked eye but some insects are able to see them.

Like in a fluorescent light bulb, ultraviolet or UV lights stimulates the coating of the tube to emit light.

5 0

4 years ago

Assign a positive velocity to the red box and negative velocity to the blue box. Are they moving in opposite direction?

attashe74 [19]

Answer:

<em>Yes, they are moving in opposite direction one to the other.</em>

Explanation:

Velocity is a vector quantity, which means that it has both magnitude and direction. The magnitude shows the size of the velocity, and the direction shows which way it is moving in reference to a chosen reference direction. If the red box is assigned a positive velocity, and the blue box is assigned a negative velocity, as indicated in the question, then it means that the red box, and the blue box, both move in opposite direction to the other.

4 0

3 years ago