7. A box is being pushed from the left at 15N and pushed from the right at 10N,

Block A, with mass mA, is initially at rest on a horizontal floor. Block B, with mass mB, is initially at rest on the horizontal

nexus9112 [7]

Answer:

(E) μs(mA +mB)g

Explanation:

We can apply for mB:

∑ Fx = mB*a (→)

⇒ Ffriction = mB*a ⇒ a = Ffriction / mB = μs*N / mB

⇒ a = μs*(mB*g) / mB ⇒ a = μs*g (acceleration of the system)

Now, for mA we have

∑ Fx = mA*a (→)

F - Ffriction = mA*a ⇒ F = mA*a + Ffriction

⇒ F = mA*(μs*g) + μs*(mB*g) ⇒ F = μs*g*(mA + mB)

We must know that the friction acts only between the two blocks

8 0

3 years ago

Atoms in a solid are not stationary, but vibrate about their equilibrium positions. Typically, the frequency of vibration is abo

hoa [83]

To develop this problem it is necessary to use the equations of description of the simple harmonic movement in which the acceleration and angular velocity are expressed as a function of the Amplitude.

Our values are given as

$f = 4.11 *10^{12} Hz$

$A = 1.23 * 10^{-11}m$

The angular velocity of a body can be described as a function of frequency as

$\omega = 2\pi f$

$\omega = 2\pi 4.11 *10^{12}$

$\omega=2.582*10^{13} rad/s$

PART A) The expression for the maximum angular velocity is given by the amplitude so that

$V = A\omega$

$V =( 1.23 * 10^{-11})(2.582*10^{13})$

$V = = 317.586m/s$

PART B) The maximum acceleration on your part would be given by the expression

$a = A \omega^2$

$a =( 1.23 * 10^{-11})(2.582*10^{13})^2$

$a= 8.2*10^{15}m/s^2$

4 0

3 years ago

Carbon-14 is used to determine the time an organism was living. The amount of carbon-14 an organism has is constant with the atm

lutik1710 [3]

Answer:

The age of the organism is approximately 11460 years.

Explanation:

The amount of carbon-14 decays exponentially in time and is defined by the following equation:

$\frac{n(t)}{n_{o}} = e^{-\frac{t}{\tau} }$ (1)

Where:

$n_{o}$ - Initial amount of carbon-14.

$n(t)$ - Current amount of carbon-14.

$t$ - Time, measured in years.

$\tau$ - Time constant, measured in years.

Then, we clear the time within the formula:

$t = -\tau \cdot \ln \frac{n(t)}{n_{o}}$ (2)

In addition, time constant can be calculated by means of half-life of carbon-14 ( $t_{1/2}$ ), measured in years:

$\tau = \frac{t_{1/2}}{\ln 2}$

If we know that $\frac{n(t)}{n_{o}} = 0.25$ and $t_{1/2} = 5730\,yr$ , then the age of the organism is:

$\tau = \frac{5730\,yr}{\ln 2}$

$\tau \approx 8266.643\,yr$

$t = -(8266.643\,yr)\cdot \ln 0.25$

$t \approx 11460.001\,yr$

The age of the organism is approximately 11460 years.

8 0

3 years ago

Read 2 more answers

Two objects that are not initially in thermal equilibrium are placed in close contact. After a while, the temperature of the cod

Dima020 [189]

Answer:

If the temperature of the colder object rises by the same amount as the temperature of the hotter object drops, then the specific heats of both objects will be equal.

Explanation:

If the temperature of the colder object rises by the same amount as the temperature of the hotter object drops when the two objects of same mass are brought into contact, then their specific heat capacity is equal.

We can prove this by the equation of heat for the two bodies:

According to given condition,

$\Delta T_1=\Delta T_2$

$\frac{Q_1}{m_1.c_1} = \frac{Q_2}{m_2.c_2}$

when there is no heat loss from the system of two bodies then $Q_1=Q_2$

$\frac{1}{m.c_1} =\frac{1}{m.c_2}$

$\Rightarrow c_1=c_2$

Thermal conductivity is ultimately affects the rate of heat transfer, however the bodies will attain their final temperature based upon their mass and their specific heat capacities.

The temperature of the colder object will rise twice as much as the temperature of the hotter object only in two cases:

when the specific heat of the colder object is half the specific heat of the hotter object while mass is equal for both.

OR

the mass of colder object is half the mass of the hotter object while their specific heat is same.

3 0

3 years ago

Why is a rotting apple a reaction in which energy is neither absorbed nor released?

o-na [289]

Answer:

Hey

It would have to be C because no net energy is lost.

7 0

3 years ago