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2 years ago

A 40.0-kg solid cylinder is rolling across a horizontal surface at a speed of 6.0 m/s. how much work is required to stop it

1 answer:

3 0

One way of thinking of energy is to say the energy is the ability of the body to do work. If you have a body that is moving that body has kinetic energy, as said above this energy can be used to do work. The amount of work done is equal to the amount of energy that body has.
In our case cylinder has the following kinetic energy:
$E_k=m\frac{v^2}{2}\\
E_k=40\frac{6^2}{2}\\
E_k=40\cdot18\\
E_k=720$J$
And that is exaclty how much work you would have to put in to stop the cylinder.

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A 35 g steel ball is held by a ceiling-mounted electromagnet 4.0 m above the floor. A compressed-air cannon sits on the floor, 4

HACTEHA [7]

Answer:

7.9 m/s

Explanation:

When both balls collide, they have spent the same time for their motions.

Motion of steel ball

This is purely under gravity. It is vertical.

Initial velocity, u = 0 m/s

Distance, s = 4.0 m - 1.2 m = 2.8 m

Acceleration, a = g

Using the equation of motion

$s = ut+\frac{1}{2}at^2$

$2.8 \text{ m} = 0+\dfrac{gt^2}{2}$

$t = \sqrt{\dfrac{5.6}{g}}$

Motion of plastic ball

This has two components: a vertical and a horizontal.

The vertical motion is under gravity.

Considering the vertical motion,

Initial velocity, u = ?

Distance, s = 1.2 m

Acceleration, a = -g (It is going up)

Using the equation of motion

$s = ut+\frac{1}{2}at^2$

$1.2\text{ m} = ut-\frac{1}{2}gt^2$

Substituting the value of t from the previous equation,

$1.2\text{ m} = u\sqrt{\dfrac{5.6}{g}}-\dfrac{1}{2}\times g\times\dfrac{5.6}{g}$

$u\sqrt{\dfrac{5.6}{g}} = 4.0$

Taking g = 9.8 m/s²,

$u = \dfrac{4.0}{0.756} = 5.29 \text{ m/s}$

This is the vertical component of the initial velocity

Considering the horizontal motion which is not accelerated,

horizontal component of the initial velocity is horizontal distance ÷ time.

$u_h = \dfrac{4.4\text{ m}}{0.756\text{ s}} = 5.82\text{ m/s}$

The initial velocity is

$v_i = \sqrt{u^2+u_h^2} = \sqrt{(5.29\text{ m/s})^2+(5.82\text{ m/s})^2} = 7.9 \text{ m/s}$

4 0

2 years ago

During a hurricane, the atmospheric pressure inside a house may blow off the roof because of the reduced pressure outside. If ai

m_a_m_a [10]

Answer:

817.5 Pa

Explanation:

From Bernoulli's equation, considering thst there is no height difference then

P1+½d(v1)²=P2+½d(v2)²

P1-P2=½d(v2²-v1²)

∆P=½d(v2²-v1²)

Where P represent pressure, d is density and v is velocity. Subscripts 1 and 2 represent inside and outside. ∆P is tge change in pressure

Given the speed at roof top as 128 km/h, we convert it to m/s as follows

128*1000/3600=35.555555555555=35.56 m/s

Velocity at the bottom of roof is 0 m/s

Density is given as 1.293 kg/m³

∆P=½*1.293*(35.56²-0)=817.5 Pa

5 0

2 years ago

A wheel completes 5.6 revolutions in 8 seconds.

nevsk [136]

Answer:

$86.15\pi rad/min$

Explanation: Angular velocity is the number of revolutions made per unit time.

We convert the number of revolutions to radians and the time given in seconds to minutes,

Given;

$1rev=2\pi rad\\therefore\\5.6rev=5.6*2\pi rad\\= 11.2\pi rad$

Also,

60s = 1 min

hence

$8s=\frac{8}{60}min\\=0.13min$

We now divide the number of revolution in radians by the time in minutes.

$\omega =\frac{11.2\pi}{0.13min}\\\omega=86.15\pi rad/min$

5 0

2 years ago

Read 2 more answers

We can block light by placing obstacles in its path, but it’s much more difficult to block sound. Why?

Flauer [41]

<h3>Answer;</h3>

B. Sound waves can move through various mediums.

<h3>Explanation;</h3>

A wave is a transmission of a disturbance from one point to another. It involves transmission of energy from the source to another point.
A wave may or may not require a medium for transmission. Waves that require medium for transmission are called mechanical waves and those that do not require medium for transmission are known as electromagnetic waves.
Light is an example of electromagnetic wave therefore it can be blocked when obstacles are placed on its path. However, for the case of sound waves, they can not be blocked by an obstacle as sound would travel through the medium used to block.

8 0

2 years ago

Read 2 more answers

Optical tweezers use light from a laser to move single atoms and molecules around. Suppose the intensity of light from the tweez

Zanzabum

(a) $3.3\cdot 10^{-6} Pa$