A train travels 24 miles in 30 minutes calculate its average speed

What is the minimum work needed to push a 920-kg car 310 m up along a 6.5 ∘incline? Ignore friction.Express your answer using tw

AVprozaik [17]

Answer:

2800000J

Explanation:

Parameters given:

Mass = 920kg, weight = 920 * 9.8 = 9016N

Distance = 310m

Angle of inclination = 6.5°

Work done is given as :

W = F*d*cosA

Where A = angle of inclination

W = (9016 * 310 * cos6.5)

W = 2776993.59J

In 2 significant figures, W = 2800000J

7 0

3 years ago

Consider a motor that exerts a constant torque of 25.0 nâ‹…m to a horizontal platform whose moment of inertia is 50.0 kgâ‹…m2. A

Crazy boy [7]

Answer:

W = 1884J

Explanation:

This question is incomplete. The original question was:

<em>Consider a motor that exerts a constant torque of 25.0 N.m to a horizontal platform whose moment of inertia is 50.0kg.m^2 . Assume that the platform is initially at rest and the torque is applied for 12.0rotations . Neglect friction. </em>

<em> How much work W does the motor do on the platform during this process? Enter your answer in joules to four significant figures.</em>

The amount of work done by the motor is given by:

$W=\Delta K$

$W= 1/2*I*\omega f^2-1/2*I*\omega o^2$

Where I = 50kg.m^2 and ωo = rad/s. We need to calculate ωf.

By using kinematics:

$\omega f^2=\omega o^2+2*\alpha*\theta$

But we don't have the acceleration yet. So, we have to calculate it by making a sum of torque:

$\tau=I*\alpha$

$\alpha=\tau/I$ => $\alpha = 0.5rad/s^2$

Now we can calculate the final velocity:

$\omega f = 8.68rad/s$

Finally, we calculate the total work:

$W= 1/2*I*\omega f^2 = 1883.56J$

Since the question asked to "<em>Enter your answer in joules to four significant figures.</em>":

W = 1884J

3 0

3 years ago

Which statement explains the polarity of a water molecule?

timofeeve [1]

Answer:

D. The oxygen side is partially negative because electrons are pulled toward the oxygen side.

Explanation:

The water molecule is polar by the virtue of covalent bonds and the hydrogen bonds within and between its molecule.

The oxygen side is partially negative because the electrons are pulled toward the oxygen side.

Between oxygen and hydrogen that makes up the water molecule, oxygen is more electronegative.

An electronegative atom has more affinity for electrons. Since the electrons in the molecule of water is shared between hydrogen and oxygen, the more electronegative specie which is water draws the electron more to itself.

This leaves a net negative charge on the oxygen atom.

8 0

3 years ago

A 3.0-kilogram mass is traveling in a circle of

dmitriy555 [2]

Answer:

$a=20\ m/s^2$

Explanation:

Given that,

The mass of an object, m = 3 kg

The radius of a circle, r = 0.2 m

The speed of the object, v = 2 m/s

We need to find the centripetal acceleration. Its formula is given by :

$a=\dfrac{v^2}{r}\\\\a=\dfrac{(2)^2}{0.2}\\\\a=20\ m/s^2$

So, the centripetal acceleration is $20\ m/s^2$ .

4 0

3 years ago

A marble rolls off a tabletop 1.15 m high and hits the floor at a point 4 m away from the tables edge in the

GREYUIT [131]

A marble rolls off a tabletop 1.15 m high and hits the floor at a point 4 m away from the edge of the table in the horizontal direction,

t= 0.45 seconds.
V=2.22m/s
VT=4.95 m/s

This is further explained below.

<h3>What is its speed when it hits the floor...?</h3>

Generally, the equation for motion is mathematically given as

S= ut + 0.5at²

Therefore

y = Voy t + 0.5gt^2

1 = 0.5x 98 x 6²

1=4.9t^2

$t=\sqrt{0.2041 }$

t= 0.45 seconds.

b) Horizontal motions are uniform.

V=Horizontal displacement/time

V=1/0.45

V=2.22m/s

C)

Vx: 2.22 m/s At bottom,

Vy² = Voy² + 2as

Vy² = 2x95x1

Vy² = 19.6

Total velocity

$VT=\sqrt{( 2.22 m/)^2+19.6}$

VT=4.95 m/s