What is one example of refraction

A 1300-N crate rests on the floor. How much work is required to move it at constant speed (a)

kherson [118]

a) The work done is 920 J

b) The work done is 5200 J

Explanation:

a)

In this first part of the problem, the crate is moved horizontally at constant speed.

The work required in this case is given by

$W=Fd cos \theta$

where

F is the magnitude of the force applied

d is the displacement of the crate

$\theta$ is the angle between the direction of the force and of the displacement

Here the crate is moved at constant speed: this means that the acceleration of the crate is zero, and so according to Newton's second law, the net force on the crate is zero: this means that the force applied, F, must be equal to the force of friction (but in opposite direction), so

F = 230 N

The displacement is

d = 4.0 m

And the angle is $\theta=0^{\circ}$ , since the force is applied horizontally. Therefore, the work done is

$W=(230)(4.0)(cos 0^{\circ})=920 J$

b)

In this case, the crate is moved vertically. The force that must be applied to lift the crate must be equal to the weight of the crate (in order to move it a constant speed), therefore

F = W = 1300 N

The displacement this time is again

d = 4.0 m

And the angle is $\theta=0^{\circ}$ , since the force is applied vertically, and the crate is moved also vertically. Therefore, the work done on the crate this time is

$W=(1300)(4.0)(cos 0^{\circ})=5200 J$

Learn more about work:

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4 0

3 years ago

In operant conditioning, generalization occurs when

Vitek1552 [10]

Typically occurs when we associate things to other things that look alike. We see that in many experiments, specifically “Little Albert” who was conditioned to be afraid of rats but later was afraid of anything that resembled that of a rat.
Hope this helps!

5 0

2 years ago

Write short notes on:<br>human made wetland

kogti [31]

Any type of wetland that has been developed or maintained by humans for uses such as aquaculture, irrigation, or water storage.

<h3>What is a human-made wetland ?</h3>

Any kind of wetland that has been created or kept up by people for purposes like water storage, irrigation, or aquaculture.

In India's Punjab state, in the Kapurthala district, lies the man-made Kanji Wetland, which includes the Kanji Lake.

In order to give irrigation facilities to the hinterland, it was built by building the headworks over the perennial Bien River, a tributary of the Beas River.

The Sunderbans are India's biggest wetland. The world's biggest mangrove forest includes Sunderban Wetland.

Hence, the human-made wetland is an artificial wetland.

To learn more about the human-made wetland refer;

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4 0

2 years ago

How to do this question

Anna71 [15]

Answer:

(a) 10 m/s

(b) 22.4 m/s

Explanation:

(a) Draw a free body diagram of the car when it is at the top of the loop. There are two forces: weight force mg pulling down, and normal force N pushing down.

Sum of forces in the centripetal direction (towards the center):

∑F = ma

mg + N = mv²/r

At minimum speed, the normal force is 0.

mg = mv²/r

g = v²/r

v = √(gr)

v = √(10 m/s² × 10.0 m)

v = 10 m/s

(b) Energy is conserved.

Initial kinetic energy + initial potential energy = final kinetic energy

½ mv₀² + mgh = ½ mv²

v₀² + 2gh = v²

(10 m/s)² + 2 (10 m/s²) (20.0 m) = v²

v = 22.4 m/s

4 0

3 years ago

Which kind of pigment reflects two primary light colors and absorbs one?1) primary pigment2) secondary pigment3) complementary p

weqwewe [10]

The primary colors of light are red, blue and green.

There are the pigments like yellow, magenta and cyan that are the mixture of two primary colors.

For example, magenta is a mixture of red and blue color. Thus, it reflects the red and blue color. Also, magneta absorbs the green color.

These type of colors that reflects two primary colors and absorb one color are known as secondary pigments.

Hence, 2nd option is the correct answer.

8 0

8 months ago