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3 years ago

14

Jordana pulled a muscle while running at a track meet. Her coach gave her a self-heating pack to treat the injury. The instructi

ons on the box said to twist the pack until the liquids mix. Which type of energy contained in the pack is responsible for producing the heat?

1 answer:

pochemuha3 years ago

6 0

Answer:

Chemical

Explanation:

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A 250 kg flatcar 25 m long is moving with a speed of 3.0 m/s along horizontal frictionless rails. A 61 kg worker starts walking

Anna11 [10]

Answer:

x=31.09m

Explanation:

p1=p2

The momentum of flatcar and the momentum of the worker so

The velocity of the worker is:

$m_{f}*v_{f}=m_{w}*v_{w}\\\\v_{f}=\frac{m_{f}*v_{f}}{m_{w}}\\v_{f}=\frac{61kg*3.0\frac{m}{s}}{250kg}\\v_{f}=0.732\frac{m}{s}$

The total motion has a total velocity and is

$Vt=v_{w}+v_{f}\\Vt=0.732\frac{m}{s}+3.0\frac{m}{s}\\Vt=3.732\frac{m}{s}$

The time the worker take walking is

$t=\frac{x}{v_{w}}\\t=\frac{25m}{3\frac{m}{s}}=8.33s$

Now the total time and the total velocity determinate the motion of tha flatcar how far has moved

$x=t*Vt\\x=8.33s*3.732\frac{m}{s} \\x=31.09m$

5 0

3 years ago

What is the value for the kinetic energy for a n = 5 Bohr orbit electron in zeptoJoules?

Ne4ueva [31]

Answer:

The kinetic energy is 86.6 zepto joules.

Explanation:

Given that,

Number of orbit n =5

We know that,

Bohr's radius for hydrogen atom is

$r = 0.53\times10^{-10}\times n^2\ m$

Now, put the value of n in the formula of radius

$r=0.53\times10^{-10}\times5^2$

$r =1.33\times10^{-9}\ m$

We need to calculate the kinetic energy

Using formula of kinetic energy

$E_{k}=\dfrac{1}{4\pi\epsilon_{0}}\times\dfrac{e^2}{2\times r_{s}}$

Put the value into the formula

$E_{k}=\dfrac{9\times10^{9}\times(1.6\times10^{-19})^2}{2\times1.33\times10^{-9}}$

$E_{k}=8.66\times10^{-20}\ J$

We know that,

$1\ zepto\ joule=1\times10^{-21}\ J$

The kinetic energy is

$E_{k}=\dfrac{8.66\times10^{-20}}{1\times10^{-21}}$

$E_{k}=86.6\ zepto\ Joules$

Hence, The kinetic energy is 86.6 zepto joules.

8 0

3 years ago

What will the stopping distance be for a 2,000-kg car if -2,000 N of force are applied when the car is traveling 20 m/s?

astraxan [27]

Answer is B- 200 m

Given:

m (mass of the car) = 2000 Kg

F = -2000 N

u(initial velocity)= 20 m/s.

v(final velocity)= 0.

Now we know that

<u>F= ma</u>

Where F is the force exerted on the object

m is the mass of the object

a is the acceleration of the object

Substituting the given values

-2000 = 2000 × a

a = -1 m/s∧2

Consider the equation

<u>v=u +at</u>

where v is the initial velocity

u is the initial velocity

a is the acceleration

t is the time

0= 20 -t

t=20 secs

s = ut +1/2(at∧2)

where s is the displacement of the object

u is the initial velocity

t is the time

v is the final velocity

a is the acceleration

s= 20 ×20 +(-1×20×20)/2

<u>s= 200 m</u>

3 0

3 years ago

Read 2 more answers

A charged particle moves in a circular path in a uniform magnetic field.Which of the following would increase the period of the

Bond [772]

Answer:

Increasing its charge

Increasing the field strength

Explanation:

For a charged particle moving in a circular path in a uniform magnetic field, the centripetal force is provided by the magnetic force, so we can write:

$qvB = m\frac{v^2}{r}$

where

q is the charge

v is the velocity

B is the magnetic field

m is the mass

r is the radius of the orbit

The period of the motion is

$T=\frac{2\pi r}{v}$

Re-arranging for r

$r=\frac{Tv}{2\pi}$

And substituting into the previous equation

$qvB = m \frac{Tv^3}{2\pi}$

Solving for T,

$T=\frac{2\pi q B}{m v^2}$

So we see that the period is:

- proportional to the charge and the magnetic field

- inversely proportional to the mass and the square of the speed

So the following will increase the period of the particle's motion:

Increasing its charge

Increasing the field strength

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3 years ago

Determining the pH of substances such as purple grape juice and catsup using test strips can be difficult. Why?

Charra [1.4K]

Answer:

Because they would naturally dye the test strips in the colors violet and red, regardless of their pH values

(would really appreciate the brainliest)

4 0

3 years ago