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zhannawk [14.2K]
11 months ago
8

Calculate the initial speed of a box which slides on a horizontal floor surface and comes to rest after sliding 2 s. The coeffic

ient of kinetic friction between the box and the surface is 0.25. (g=9.8 ms-2).
Physics
1 answer:
NARA [144]11 months ago
3 0

A box sliding on a horizontal floor surface starts out moving at 4.9 m/s and stops after 2 seconds. The surface and the box have a kinetic friction has friction coefficient of 0.25 (g=9.8 ms-2).

The speed of an object at the start of a measurement, or an initial state, is known as the initial speed. The ratio of distance travelled to travel time, also known as the average speed, is the sum of the initial and final speeds. The difference between initial and ending speeds is the speed change. A force that acts between moving surfaces is referred to as kinetic friction. A force acting in opposition to the direction of a moving body on the surface is felt.

Interval (t) equals 2 seconds

Kinetic friction coefficient is 0.25.

gravity-induced acceleration (g) = 9.8 m/s2.

Coming to a stop at a final velocity  of 0 m/s.

Regular force  equals mg

Kinetic friction force is given by  = k.

N = μkmg

I = (delta P) (delta P)

Vo = (0.25)(9.8)(2) (2)

Vo = 4.9m/s

Learn more about kinetic friction here

brainly.com/question/17237604

#SPJ4

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Light waves travel in straight lines in all directions from the source of the light, unless
Ainat [17]

A.  the medium through which the light travels changes.

Explanation:

Light waves will continue to travel in a straight line in all directions from their source unless the medium through which the light travels changes.

A change in medium causes light to exhibit different properties. Also, when light hits an obstacle, they can be diffracted.

  • The way light travels on crossing a boundary differs.
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6 0
3 years ago
. If she
I am Lyosha [343]

Answer:

9 meters

Explanation:

Given:

Mass of Avi is, m=40\ kg

Spring constant is, k=176,400\ N/m

Compression in the spring is, x=20\ cm=0.20\ m

Let the maximum height reached be 'h' m.

Now, as the spring is compressed, there is elastic potential energy stored in the spring. This elastic potential energy is transferred to Avi in the form of gravitational potential energy.

So, by law of conservation of energy, decrease in elastic potential energy is equal to increase in gravitational potential energy.

Decrease in elastic potential energy is given as:

EPE=\frac{1}{2}kx^2\\EPE=\frac{1}{2}\times 176400\times (0.20)^2\\EPE=88200\times 0.04=3528\ J

Now, increase in gravitational potential energy is given as:

GPE=mgh=40\times 9.8\times h=392h

Now, increase in gravitational potential energy is equal decrease in elastic potential energy. Therefore,

392h=3528\\\\h=\frac{3528}{392}\\\\h=9\ m

Therefore, Avi will reach a maximum height of 9 meters.

6 0
3 years ago
You are an engineer in charge of designing a new generation of elevators for a prospective upgrade to the Empire State Building.
DanielleElmas [232]

Answer:

   t_total = 23.757 s

Explanation:

This is a kinematics exercise.

Let's start by calculating the distance and has to reach the limit speed of

v = 18.8 m / s

         v = v₀ + a t₁

the elevator starts with zero speed

         v = a t₁

         t₁ = v / a

         t₁ = 18.8 / 2.40

         t₁ = 7.833 s

in this time he runs

         y₁ = v₀ t₁ + ½ a t₁²

         y₁ = ½ a t₁²

         y₁ = ½ 2.40 7.833²

         y₁ = 73.627 m

This is the time and distance traveled until reaching the maximum speed, which will be constant throughout the rest of the trip.

           x_total = x₁ + x₂

           x₂ = x_total - x₁

           x₂ = 373 - 73,627

           x₂ = 299.373 m

this distance travels at constant speed,

           v = x₂ / t₂

           t₂ = x₂ / v

           t₂ = 299.373 / 18.8

           t₂ = 15.92 s

therefore the total travel time is

           t_total = t₁ + t₂

           t_total = 7.833 + 15.92

           t_total = 23.757 s

6 0
3 years ago
In order to do work, the force vector must be
gregori [183]

As we know that total work done by a force is given by

W = F.d

W = Fdcos\theta

so it is product of force and displacement along same direction

as we can write it as

W = (Fcos\theta)(d)

so it must be the product of force and displacement in same directions so correct answer must be

<u>B. in the same direction as the displacement vector and the motion.</u>

6 0
3 years ago
Read 2 more answers
Consider a father pushing a child on a playground merry-go-round. The system has a moment of inertia of 84.4 kg.m^2. The father
Sophie [7]

Answer:

Explanation:

Given that:

the initial angular velocity \omega_o = 0

angular acceleration \alpha = 4.44 rad/s²

Using the formula:

\omega = \omega_o+ \alpha t

Making t the subject of the formula:

t= \dfrac{\omega- \omega_o}{ \alpha }

where;

\omega = 1.53 \ rad/s^2

∴

t= \dfrac{1.53-0}{4.44 }

t = 0.345 s

b)

Using the formula:

\omega ^2 = \omega _o^2 + 2 \alpha \theta

here;

\theta = angular displacement

∴

\theta = \dfrac{\omega^2 - \omega_o^2}{2 \alpha }

\theta = \dfrac{(1.53)^2 -0^2}{2 (4.44) }

\theta =0.264 \ rad

Recall that:

2π rad = 1 revolution

Then;

0.264 rad = (x) revolution

x = \dfrac{0.264 \times 1}{2 \pi}

x = 0.042 revolutions

c)

Here; force = 270 N

radius = 1.20 m

The torque = F * r

\tau = 270 \times 1.20 \\ \\  \tau = 324 \ Nm

However;

From the moment of inertia;

Torque( \tau) = I \alpha \\ \\  Since( I \alpha) = 324 \ Nm. \\ \\  Then; \\ \\  \alpha= \dfrac{324}{I}

given that;

I = 84.4 kg.m²

\alpha= \dfrac{324}{84.4} \\ \\  \alpha=3.84 \ rad/s^2

For re-tardation; \alpha=-3.84 \ rad/s^2

Using the equation

t= \dfrac{\omega- \omega_o}{ \alpha }

t= \dfrac{0-1.53}{ -3.84 }

t= \dfrac{1.53}{ 3.84 }

t = 0.398s

The required time it takes= 0.398s

5 0
2 years ago
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