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vlada-n [284]
3 years ago
8

A horizontal applied force of magnitude 25 N acts on a block sliding on a horizontal surface. The force of friction between the

block and the surface has magnitude 8 N. If the direction of the applied force is reversed which of the following is true?
A. the magnitude of the velocity of the block will remain constant.
B. the magnitude of the acceleration of the block decreases
C. The magnitude of the net force on the block increases as compared to before.
D. the magnitude of the net force on the block will remain the same as before​
Physics
1 answer:
kompoz [17]3 years ago
3 0

' A ' and ' D ' are both correct statements.

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What's Inertia ????☁️☁️​
Assoli18 [71]

Explanation:

the inability to change the position from rest to motion or motion to rest by themselves is inertia.

3 0
3 years ago
A CD has to rotate under the readout-laser with a constant linear velocity of 1.25 m/s. If the laser is at a position 3.7 cm fro
Savatey [412]

Answer:N=322.53 rpm

Explanation:

Given

Linear velocity (v)=1.25 m/s

Position from center is 3.7 cm

we know

v=\omega \times r

1.25\times 100=\omega \times 3.7

\omega =\frac{125}{3.7}=33.78

and \frac{2\pi N}{60}=\omega

N=\frac{\omega \times 60}{2\pi }

N=\frac{33.78\times 60}{2\pi }

N=322.53 rpm

8 0
3 years ago
If blue light hits a red filter, what kind of light comes through the filter?
kotegsom [21]
It can be either C or B

Reasons it can be C: Red and Blue together(if I'm correct in art) is the combined color of two of the 3 primary colors to get a purple/violet color and if said filter is see through or just too dense for the light to even penetrate the said filter(in theory) but all in all purple is the answer with the two primary colors blue and red.

But also, it depends on what kind of filter it is, if the filter is like a screen filter then it will just come out in blue with the slightly different colors of again purple but in a darker tone then the actual eye can see.

Or it can be just C again cause the filter can be a film but that's a bit too far and to complex for right now so I believe it is B
8 0
3 years ago
The velocity of an object is v(t) = 27 − t2, 0 ≤ t ≤ 6 where v is measured in meters per second and t is the time in seconds.
arlik [135]

Answer:

(a) 23 m/s, -4 m/s²

(b) Speed is decreasing.

Explanation:

The velocity of the object is given as:

v(t) = 27 - t²

When t = 2 secs, velocity, v(2) becomes:

v(2) = 27 - (2)²

v(2) = 27 - 4

v(2) = 23 m/s

The acceleration is the first derivative of the velocity, dv/dt:

a(t) = dv(t)/dt = -2t

Acceleration after 2 secs, a(2) is:

a(2) = -2*2

a(2) = -4 m/s²

(b) When velocity and acceleration have opposite signs, it means that the velocity and acceleration are in opposite directions, hence, the object is slowing down.

In other words, the speed is decreasing.

8 0
3 years ago
Una mujer de masa m está parada en el borde de una mesa giratoria horizontal de momento de inercia I y radio R. La mesa al princ
Dovator [93]

r

- \frac{mR^2 }{I  } \ vAnswer:

a)      w = - \frac{m r }{I} v  ,  b)   W = - ½ m_woman R² (1 + m_woman R / I²) v²

Explanation:

a) To solve this exercise, let's use the conservation of angular momentum.

We define a system formed by the table and the woman, therefore the torques are internal and the moment is conserved

initial instant. Before starting to move the woman

         L₀ = 0

final instant. After starting to move

         L_f = I w + m v r

the moment is preserved

        L₀ = L_f

         0 = Iw + m v r

         w = - \frac{m r }{I} v                    (1)

the direction of the angular velocity is opposite to the direction of the linear velocity, that is, counterclockwise

b) for this part we use the relationship between work and kinetic energy

        W = ΔK

in this case the initial speed is zero and the final speed of the table, using the relationship between linear and angular variables

         v = w r

we substitute

          W = 0 - ½ I_total w²

          I_total = I + m_{woman} R²

          W = - ½ (I + m_woman R²)  ( \frac{m_{woman} R}{I} \ v) ²

          W = - ½ (m_woman² R² + m_woman³ R³ / I²) v²

          W = - ½ m_woman R² (1 + m_woman R / I²) v²

3 0
3 years ago
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