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yawa3891 [41]
2 years ago
6

A 20 kg crate initially at rest on a horizontal floor requires a 80 N horizontal force to set it in motion. Find the coefficient

of static friction between the crate and the floor.​
Physics
1 answer:
e-lub [12.9K]2 years ago
7 0

Answer:

<em>The coefficient of static friction between the crate and the floor is 0.41</em>

Explanation:

<u>Friction Force</u>

When an object is moving and encounters friction in the air or rough surfaces, it loses acceleration and velocity because the friction force opposes motion.

The friction force when an object is moving on a horizontal surface is calculated by:

Fr=\mu N          [1]

Where \mu is the coefficient of static or kinetics friction and N is the normal force.

If no forces other then the weight and the normal are acting upon the y-direction, then the weight and the normal are equal in magnitude:

N = W = m.g

The crate of m=20 Kg has a weight of:

W = 20*9.8

W = 196 N

The normal force is also N=196 N

We can find the coefficient of static friction by solving [1] for \mu:

\displaystyle \mu=\frac{Fr}{N}

The friction force is equal to the minimum force required to start moving the object on the floor, thus Fr=80 N and:

\displaystyle \mu=\frac{80}{196}

\mu=0.41

The coefficient of static friction between the crate and the floor is 0.41

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A skater is using very low friction rollerblades. A friend throws a Frisbee at her, on the straight line along which she is coas
kupik [55]

Answer:

a)  perfectly inelastic,  b)  collision is inelastic,  c)   elastic  

Explanation:

In this exercise, it is asked to identify what type of shock occurs between the skater and the frisbee, for this we must define a system formed by the skater and the fribee, so that the forces during the crash have been internal and the amount of movement is preserved

Initial instant. Before the skater touches the frisbee

    p₀ = M v₁ + m v₂

where M and m are the masses of the skater and frisbee, respectively

for the final moment they give us several possibilities, in all case the moment is conserved

       p₀ = p_{f}

case a)

Final instant. grabs the frisbee and holds it

    p_{f} = (M + m) v '

     p₀ = p_{f}

We can see that this shock is perfectly inelastic, it holds the fressbee

case b)

final instant.

This case is similar to the previous one, but the final speed of fresbee is zero, therefore this collision is inelastic and the kinetic energy is not conserved.

case c)

final instant. Grab the fressbee and resend it

      p_{f} = M v_{1f} + m v_{2f}

this is an elastic Shock since the equivalent of a rebound of the fressbee, the kinetic energy is conserved.

5 0
2 years ago
A quantitative description of kinematics involves using ___ th describe the motion
Semmy [17]

Answer:

numbers

Explanation:

Virtually all unimaginable processes can be described as the movement of certain objects. To analyze and predict the nature of the movements that result from the different kinds of interactions, some important concepts such as momentum, force and energy have been invented. If momentum, force, and energy are known and expressed in a quantitative way (that is, by numbers) it is possible to establish rules by which the resulting movements can be predicted.

4 0
2 years ago
On a caterpillars map all distances are marked in kilometers . The caterpillars map shows the distance between two milkweed plan
frutty [35]

Answer:

The distance in kilometers is 4012 ×10^{-6} km.

Explanation:

We know that the conversion of 1 millimeters is equal to 10^{-3} meter. And then the conversion of 1 meter is equal to 10^{-3} km. Then the conversion of 1 millimeter to km will be

1 mm = 10^{-3} m

1 m = 10^{-3} km

So, 1 mm = 10^{-3}×10^{-3} km = 10^{-6} km.

As here the the distance is 4012 mm, then the distance in km will be

4012 mm = 4012 ×10^{-6} km.

So the distance is 4012 ×10^{-6} km.

5 0
2 years ago
determine the greates possile acceleration of the 975 kg race car so that its front wheels do not leace the gorund
wolverine [178]

<u>Answer</u>:

The greatest possible acceleration of the car is a_G= 6.78 m/s^2

<u>Explanation</u>:

N_A+N_B-Mg = 0

-N_Aa +N_B(b-a)- \mu_s N_Bh - \mu_s N_Ah = 0

0.8N_B +0.8N_A = 975a_G

N_A+N_B = 9564.75 -------------(1)

-N_A(1.82) + N_B(2.20 -1.82) -0.9N_B(0.55)-0.8N_A(0.55)=0

-N_A(1.82) +0.38 N_B -0.44N_B -0.44N_A=0

-2.26N_A -0.06N_B= 0 ----------------(2)

Solving the equation (1) and(2)

N_A + N_B = 9564.75

-2.26N_A-0.06N_B=0

N_A = -260.85N

N_B = 9825.60N

\mu_s N_B + \mu_s N_A = 975a_G

0.8(9825.60)+0.8(-260.85) = 975a_Ga_G=\frac{7651.8}{975}a_G_1=7.4848m/s^2

Next lets assume that the front wheels contact with the ground N_A = 0

F_B = Ma_G

N_B = M_g

N_B - M_g = 0

N_B(b-a) –F_Bh = 0

F_B = 975a_G

N_B-975(9.8) = 0

N_B=9564.75N

9564.75(2.20 -1.82) -F_B(0.55)=0

\frac{3634.605}{0.55}=F_B

F_B = 6608.3

F_B = Ma_G

6608.3 = 975a_G

a_G = 6.7778 m/s^2

a_G_2 = 6.78m/s^2

Choosing the critical case

a_G = min(a_G_1 ,a_G_2)

a_G = min(7.848, 6.78)

a_G= 6.78 m/s^2

3 0
3 years ago
A description of both speed and direction
julia-pushkina [17]
Speed most often describes acceleration or a high rate of motion. ... As a verb, it means to “move along quickly,” like how you speed around on your bike. Direction is defined as the path that something takes, the path that must be taken to reach a specific place, the way in which something is starting to develop or the way you are facing
7 0
3 years ago
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