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Vesna [10]
3 years ago
14

A box of mass 12 kg is at rest on a flat floor. The coefficient of static friction between the box and floor is 0.42. What is th

e minimum force needed to set the box in motion across the floor?
Physics
2 answers:
Trava [24]3 years ago
7 0

Answer: 50.4N

Explanation:

Frictional force (Ff) is the force that opposes the moving force acting on a body.

This frictional force (Ff) is the product of the coefficient of friction(n) and normal reaction (R)

Mathematically, Fm = Ff = nR (since both forces are equal and opposite forces along the horizontal axis.)

NB: Fm = Ff (true for static bodies only)

Also note that the weight (W) of the body will be equal to the normal reaction (R) (forces acting along the y axis on the body) i.e W = R

R = Weight = mg = 12×10 = 120N

n = 0.42

Substituting the datas given into the formula of friction force

Ff = nR = Fm

Fm = 0.42×120

Fm = 50.4N

Therefore the minimum force needed to set the box in motion across the floor is 50.4N

Oxana [17]3 years ago
5 0
The maximum static force that can be applied is equal to the normal force*the frictional force. the normal force on the box is equal to mg since the floor is flat using 9.81m/s^2 for gravity 12kg*9.81m/s^2 = 118N multiplying the normal force by the frictional force you get a 118*.42= 49.6N so overcome the force of static friction on the box a minimum of 49.6N would need to be applied.
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A 0.600 m long pendulum is used to determine the acceleration due to gravity on a distant plane. If 20 oscillations are complete
katrin2010 [14]

Answer:

7.50 m/s^2

Explanation:

The period of a pendulum is given by:

T=2\pi \sqrt{\frac{L}{g}} (1)

where

L = 0.600 m is the length of the pendulum

g = ? is the acceleration due to gravity


In this problem, we can find the period T. In fact, the frequency is equal to the number of oscillations per second, so:

f=\frac{N}{t}=\frac{20}{35.5 s}=0.563 Hz

And the period is the reciprocal of the frequency:

T=\frac{1}{f}=\frac{1}{0.563 Hz}=1.776 s

And by using this into eq.(1), we can find the value of g:

g=\frac{4 \pi^2 L}{T^2}=\frac{4 \pi^2 (0.600 m)}{(1.776 s)^2}=7.50 m/s^2

6 0
3 years ago
A cooking pot is sitting in a kitchen for several hours unused. Why does it feel cold when you touch it?
masha68 [24]

Answer:

I would go with 2

Explanation:

But i would also not go with my answer. Lol

8 0
3 years ago
A 100 N force is applied to move an object a horizontal distance of 5 meters at constant speed in 10 seconds. How much power is
Tpy6a [65]

Answer:

50 W

Explanation:

<h3><u>Given :</u></h3>

  • Force applied = 100 N
  • Distance covered = 5 metres
  • Time = 10 seconds

<h3><u>To find :</u></h3>

Power

<h3><u>Solution :</u></h3>

For calculating power, we first need to know about the work done.

\bf \boxed{Work = Force \times displacement}

Now, substituting values in the above formula;

Work = 100 × 5

= 500 Nm or 500 J

We know that,

\bf \boxed{Power=\dfrac{Work\:done}{Time\: taken}}

Substituting values in above formula;

Power = 500/ 10

= 50 Nm/s or 50 W

Hence, power = 50 W .

5 0
3 years ago
Two forces, F⃗ 1F→1F_1_vec and F⃗ 2F→2F_2_vec, act at a point. F⃗ 1F→1F_1_vec has a magnitude of 9.20 NN and is directed at an a
marishachu [46]

Answer:

-9.46 N

Explanation:

In order to get the value of the x component of the resultant force, we need to get the value of the x component of each force.

This value will be the projection of the force vector, on the x-axis.

For F₁, as it is directed at an angle of 55.0º above the negative x axis, we can find F₁ₓ just applying the definition of cosine of an angle, as follows:

cos θ = \frac{x}{r}

In this case, x = F₁ₓ, and r = F₁

θ, measured from the positive x axis counterclockwise, is as follows:

θ= 180º-55º = 125º

⇒ F₁ₓ = F₁* cosθ = 9.2 N * cos 125º = -5.28 N

We can repeat the process for F₂, as follows:

For F₂, as it is directed at an angle of 53.3º below the negative x axis, we can find F₂ₓ just applying the definition of cosine of an angle, as follows:

cos θ = \frac{x}{r}

In this case, x = F₂ₓ, and r = F₂

θ, measured from the positive x axis counterclockwise, is as follows:

θ= 180º + 53.3º = 233.3º

⇒ F₂ₓ = F₂* cosθ = 7.00 N * cos 233.3º = -4.18 N

The total component of both forces along the x axis, can be found just adding both components, as follows:

Fₓ = F₁ₓ + F₂ₓ = -5.28 N + -4.18 N = -9.46 N

5 0
3 years ago
The first antiparticle, the positron or antielectron, was discovered in 1932. It had been predicted by Paul Dirac in 1928, thoug
Taya2010 [7]

Answer:

Energy of Photon = 4.091 MeV

Explanation:

From the conservation of energy principle, we know that total energy of the system must remain conserved. So, the energy or particles before collision must be equal to the energy of photons after collision.

K.E OF electron + Rest Energy of electron + K.E of positron + Rest Energy of positron = 2(Energy of Photon)

where,

K.E OF electron = 3.58 MeV

Rest Energy of electron = 0.511 MeV

Rest Energy of positron = 0.511 MeV

K.E OF positron = 3.58 MeV

Energy of Photon = ?

Therefore,

3.58 MeV + 0.511 MeV + 3.58 MeV + 0.511 MeV = 2(Energy of Photon)

Energy of Photon = 8.182 MeV/2

<u>Energy of Photon = 4.091 MeV</u>

8 0
3 years ago
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