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djverab [1.8K]
2 years ago
7

Please help

Physics
2 answers:
vladimir2022 [97]2 years ago
5 0

Answer:

true true false true false

Greeley [361]2 years ago
4 0

Answer:

1)true

2)true

3)false

4)false

5)true

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A tradesman sharpens a knife by pushing it with a constant force against the rim of a grindstone. The 30-cm-diameter stone is sp
Lorico [155]

Answer:

a. 0.21 rad/s2

b. 2.205 N

Explanation:

We convert from rpm to rad/s knowing that each revolution has 2π radians and each minute is 60 seconds

200 rpm = 200 * 2π / 60 = 21 rad/s

180 rpm = 180 * 2π / 60 = 18.85 rad/s

r = d/2 = 30cm / 2 = 15 cm = 0.15 m

a)So if the angular speed decreases steadily (at a constant rate) from 21 rad/s to 18.85 rad/s within 10s then the angular acceleration is

\alpha = \frac{\Delta \omega}{\Delta t} = \frac{21 - 18.85}{10} = 0.21 rad/s^2

b) Assume the grind stone is a solid disk, its moment of inertia is

I = mR^2/2

Where m = 28 kg is the disk mass and R = 0.15 m is the radius of the disk.

I = 28*0.15^2/2 = 0.315 kgm^2

So the friction torque is

T_f = I\alpha = 0.315*0.21 = 0.06615 Nm

The friction force is

F_f = T_f/R = 0.06615 / 0.15 = 0.441 N

Since the friction coefficient is 0.2, we can calculate the normal force that is used to press the knife against the stone

N = F_f/\mu = 0.441/0.2 = 2.205 N

7 0
3 years ago
A certain spring exerts a nonlinear force given by F(x) = −60x − 18x2 , where x is in meters and F is in newtons. A 0.90-kg bloc
tia_tia [17]

Answer:

a)  W = 6.75 J and b) v = 3.87 m / s

Explanation:

a) In the problem the force is nonlinear and they ask us for work, so we must use it's definition

      W = ∫ F. dx

Bold indicates vectors.  In a spring the force is applied in the direction of movement, whereby the scalar product is reduced to the ordinary product

     W = ∫ F dx

We replace and integrate

    W = ∫ (-60 x - 18 x²) dx

    W = -60 x²/2 -18 x³/3

Let's evaluate between the integration limits, lower W = 0 for x = -0.50 m, to the upper limit W = W for x = 0 m

    W = -30 [0- (-0.50) 2] -6 [0 - (- 0.50) 3]

    W = 7.5 - 0.75

    W = 6.75 J

b)  Work is equal to the variation of kinetic energy

    W = ΔK

    W = ΔK = ½ m v² -0

    v =√ 2W/m

    v = √(2 6.75/ 0.90)

    v = 3.87 m / s

8 0
3 years ago
A car with an initial velocity of 5.0 is acelerated at 3.0for 4.0seconds what os the velocity of tje car ofter the 4.0seconds
sasho [114]
Vf =Vi+at
Vf= 5 + 3*4
Vf=5+12
Vf=17m/sec
6 0
3 years ago
Which of the following is a characteristic of digital data?
Westkost [7]

Answer:

duplication being slightly more expensive.

Explanation:

3 0
3 years ago
URGENT PLEASE HELP!!!! GIVING BRAINLIEST!! If you answer this correctly ill answer some of your questions you have posted! (60pt
tigry1 [53]

Answer:

Answer:

D) by using military force.

Explanation:

Typically, people like Mussolini and Stalin gain popularity in trying times by promising a type of well-being to a group or nation of stricken people, in which they gain huge amounts of popularity at once. Typically they are then elected to some seat of power, in which, with popularity and most likely the military on their side, they would overthrow the current government. The next step taken is to suppress any opposition or even those who don't fully support the party. This can be given out in two ways, which is through force (especially opposition), or providing benefits to those who are in the party (to draw those who are not exactly supporting to support for the benefits).

With "popular" support, as well as military control, the overthrow is complete, and the group is established in power.

5 0
3 years ago
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