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3 years ago

9. A force is applied horizontally to a 20 kg box on a flat table, if the acceleration of the box is 2 m/s and the

Physics

1 answer:

marysya [2.9K]3 years ago

3 0

By Newton's second law,

n + (-w) = 0

p + (-f ) = (20 kg) (2 m/s²)

where n is the magnitude of the normal force, w is the weight of the box, p is the magnitude of the applied force (p for push or pull), and f is the magnitude of the friction force.

Calculate the weight of the box:

w = (20 kg) (9.80 m/s²) = 196 N

Then

n = w = 196 N

and

f = µ n = 0.5 (196 N) = 98 N

Now solve for p :

p - 98 N = 40 N

p = 138 N

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4-12. The morning inspection of the tank farm finds a leak in the turpentine tank. The leak is repaired. An investigation finds

bonufazy [111]

Answer:

a) $V=759.8727\ ft^3$

b) $\dot V=1.403\times 10^{-3}\ ft^3.s^{-1}$

c) $t\approx29.541\ s$

Explanation:

Given:

diameter of hole in the tank, $d'=0.1\ in=\frac{1}{120}\ ft$

position of the hole form the tank bottom, $h' =7\ ft$

initial level of turpentine in the tank before the leakage, $h_i=17.3\ ft$

level of turpentine in the tank after the repair of leakage, $h_f=13\ ft$

diameter of the tank, $d=15\ ft$

density of turpentine oil, $\rho=55\ lbm.ft^3$

Now, volume of turpentine spilled:

$V=A.(h_i-h_f)$

where:

$A=$ area of the cross section of the tank's volume

$V=\pi .\frac{d^2}{4} \times(h_i-h_f)$

$V=\pi\times\frac{15^2}{4} \times(17.3-13)$

$V=759.8727\ ft^3$

When the tank was full the liquid level was highest:

so velocity form the height of the hole will be given as:

$v=\sqrt{2g.(h_i-h')}$

$v=\sqrt{2\times 32.12\times (17.3-7) }$

$v=25.722\ ft.s^{-1}$

Now we have the flow rate of the spillage given by:

$\dot V=(\pi.\frac{d'^2}{4}) \times v$

$\dot V=\pi\times \frac{(\frac{1}{120})^2 }{4} \times 25.722$

$\dot V=1.403\times 10^{-3}\ ft^3.s^{-1}$

Total time the leak was active can be calculated as:

$t=\frac{V}{\dot V}$

$t=\frac{759.8727}{25.722}$

$t\approx29.541\ s$

7 0

4 years ago

What measures the mount of displacement in a longitudinal esbelta?

Travka [436]

The amplitude. It is the displacement at a peak.

8 0

3 years ago

Why shouldn't the US government cut the space exploration budget? What are the advantages of exploring space?

insens350 [35]

The US shouldn't cut the space exploration budget because rare-earth materials are used to make shuttles and satellites.

Advantages of exploring space are:
We can learn a lot about star systems, black holes, and gravity.
We can see earth's surface and know what rival countries are doing.
We can find earth-like planets.
There are more, but these were the quickest to come to mind for me~!

4 0

3 years ago

Read 2 more answers

A 0.42 kg mass is attached to a light spring with a force constant of 34.9 N/m and set into oscillation on a horizontal friction

Whitepunk [10]

(a) 0.456 m/s

The maximum speed of the oscillating mass can be found by using the conservation of energy. In fact:

- At the point of maximum displacement, the mechanical energy of the system is just elastic potential energy:

$E=U=\frac{1}{2}kA^2$ (1)

where

k = 34.9 N/m is the spring constant

A = 5.0 cm = 0.05 m is the amplitude of the oscillation

- At the point of equilibrium, the displacement is zero, so all the mechanical energy of the system is just kinetic energy:

$E=K=\frac{1}{2}mv_{max}^2$ (2)

where

m = 0.42 kg is the mass

vmax is the maximum speed, which is maximum when the mass passes the equilibrium position

Since the mechanical energy is conserved, we can write (1) = (2):

$\frac{1}{2}kA^2=\frac{1}{2}mv_{max}^2\\v_{max}=\sqrt{\frac{kA^2}{m}}=\sqrt{\frac{(34.9 N/m)(0.05 m)^2}{0.42 kg}}=0.456 m/s$

(b) 0.437 m/s

When the spring is compressed by x = 1.5 cm = 0.015 m, the equation for the conservation of energy becomes:

$E=\frac{1}{2}kx^2+\frac{1}{2}mv^2$ (3)

where the total mechanical energy can be calculated at the point where the displacement is maximum (x = A = 0.05 m):

$E=\frac{1}{2}kA^2=\frac{1}{2}(34.9 N/m)(0.05 m)^2=0.044 J$

So, solving (3) for v, we find the speed when x=1.5 cm:

$v=\sqrt{\frac{2E-kx^2}{m}}=\sqrt{\frac{2(0.044 J)-(34.9 N/m)(0.015 m)^2}{0.42 kg}}=0.437 m/s$

(c) 0.437 m/s

This part of the problem is exactly identical to part b), since the displacement of the mass is still

x = 1.5 cm = 0.015 m

So, the speed when this is the displacement is

$v=\sqrt{\frac{2E-kx^2}{m}}=\sqrt{\frac{2(0.044 J)-(34.9 N/m)(0.015 m)^2}{0.42 kg}}=0.437 m/s$

(d) 4.4 cm

In this case, we have that the speed of the mass is 1/2 of the maximum value, so:

$v=\frac{v_{max}}{2}=\frac{0.456 m/s}{2}=0.228 m/s$

And by using the conservation of energy again, we can find the corresponding value of the displacement x:

$E=\frac{1}{2}kx^2+\frac{1}{2}mv^2\\x=\sqrt{\frac{2E-mv^2}{k}}=\sqrt{\frac{2(0.044 J)-(0.42 kg)(0.228 m/s)^2}{34.9 N/m}}=0.044 m=4.4 cm$

4 0

3 years ago

Lawerence kohl berg developed the theory of

Natali [406]

Explanation:

Kohlberg's theory of moral development is a theory that focuses on how children develop morality and moral reasoning. Kohlberg's theory suggests that moral development occurs in a series of six stages. The theory also suggests that moral logic is primarily focused on seeking and maintaining justice.

7 0

2 years ago