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sesenic [268]
4 years ago
9

When a board with a box on it is slowly tilted to larger and larger angle, common experience shows that the box will at some poi

nt "break loose" and start to accelerate down the board.The box begins to slide once the component of gravity acting parallel to the boardequals the force of static friction. Which of the following is the most general explanation for why the box accelerates down the board?(A) The force of kinetic friction is smaller than that of static friction, but Fg remains the same.(B) Once the box is moving, Fg is smaller than the force of static friction but larger than the force of kinetic friction.(C) Once the box is moving, Fg is larger than the force of static friction.(D) When the box is stationary, Fg equals the force of static friction, but once the box starts moving, the sliding reduces the normal force, which in turn reduces the friction.
Physics
1 answer:
nydimaria [60]4 years ago
6 0

Answer:

Correct option is A -  The force of kinetic friction is smaller than that of static friction, but Fg remains the same.

Explanation:

(A) The force of kinetic friction is smaller than that of static friction, but Fg remains the same

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i learned that kinetic energy is energy when an object is actually moving not including the moving particles. i also learned tha
GaryK [48]

Answer:

Part of that kinetic energy created by moving of particles in object is transformed to heat that can be measured by thermometer.

Explanation:

By moving object creates kinematic energy, that is true. In object itself small particles are moving and creating kinetic energy as well. Part of that kinetic energy created by moving of particles in object is transformed to heat that can be measured by thermometer.

Same thing is that when you run or exercise your body temperature is raising(because of moving ).

When you sit your body does not raise temperature.

6 0
3 years ago
Difference between diurnal and annual motion in two points​
Valentin [98]

Answer:

Explanation below:

Explanation:

Annual motion describes the changes in motion of the earth around the sun. Diurnal motion can be better understood as the change in motion caused by Earths rotation at the poles.

This might not be the answer you were looking for, your question is very vague.

5 0
3 years ago
A car is travelling at a constant speed of 26.5 m/s. Its tires have a radius of 72 cm. If the car slows down at a constant rate
maksim [4K]

Answer:

Magnitude of angular acceleration = -3.95 rad/s²

Explanation:

Angular acceleration is the ratio of linear acceleration and radius.

That is

        \texttt{Angular acceleration}=\frac{\texttt{Linear acceleration}}{\texttt{Radius}}\\\\\alpha =\frac{a}{r}

Radius = 72 cm = 0.72 m

Linear acceleration is rate of change of velocity.

a=\frac{11.7-26.5}{5.2}=-2.85m/s^2

Angular acceleration

        \alpha =\frac{a}{r}=\frac{-2.85}{0.72}=-3.95rad/s^2

Angular acceleration = -3.95 rad/s²  

Magnitude =  3.95 rad/s²     

4 0
3 years ago
Let's take two balls, each of radius 0.1 meters and charge them each to 3 microCoulombs. Then, let's put them on a flat surface
salantis [7]

Explanation:

First, we will calculate the electric potential energy of two charges at a distance R as follows.

                   R = 2r

                      = 2 \times 0.1 m

                      = 0.2 m

where,    R = separation between center's of both Q's. Hence, the potential energy will be calculated as follows.

                U = \frac{k \times Q \times Q}{R}

                    = \frac{8.98 \times 10^{9} \times (3 \times 10^{-6} C)^{2}}{0.1}

                    = 0.081 J

As, both the charges are coming towards each other with the same energy so there will occur equal sharing of electric potential energy between these two charges.

Therefore, when these charges touch each other then they used to posses maximum kinetic energy, that is, \frac{U}{2}.

Hence,   K.E = \frac{U}{2}

                     = \frac{0.081}{2}

                     = 0.0405 J

Now, we will calculate the speed of balls as follows.

                 V = \sqrt{\sqrt{\frac{2 \times K.E}{m}}

                     = \sqrt{\sqrt{\frac{2 \times 0.0405}{4 kg}}

                     = 0.142 m/s

Therefore, we can conclude that final speed of one of the balls is 0.142 m/s.

6 0
3 years ago
A rubber bullet of mass m=0.025\,\mathrm{kg}m=0.025kg traveling at velocity v_0 = 50\,\mathrm{m/s}v 0 ​ =50m/s hits an iron bloc
Pavel [41]

Answer: 0.001 m

Explanation:

In order to get the máximum height reached by the iron block, we can use the energy conservation principle, as all the kinetic energy impressed upon the iron blck by the rubber bullet during the collision, becomes gravitational potential energy, as follows:

½ m v2 = m. g. h (1)

We don´t know the value of v, but if we look to the collision, and we asume no external forces act during it, the total momentum must be conserved.

The initial momentum, as the block is at rest, is just the one due to the rubber bullet:

P1 = mb . vb = 0.025 kg. 50 m/s = 1.25 kg. m/s

The final momemtum, is just the sum of the one due to the bullet (after being bounced back) and the one for the iron block:

P2 = mb . vfb  + mib . vib= 0.025 Kg. (-35 m/s) + 15 Kg.vib

As we have already said, P1 = P2, so we can write the following equation:

0.025 Kg. (-35 m/s) + 15 Kg. vib = 1.25 Kg. m/s.

Solving for vib, we have:

vib = 0.14 m/s

Now, we can replace this value in the equation (1) above:

½ . 15 Kg. (0.14)2  (m/s)2 = 15 Kg. 9.8 m/s2. H

Solving for H, we have:

H = 0.001 m

3 0
3 years ago
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