Which of the following is required for U.S. citizens to travel outside the United States?

Railroad cars are loosely coupled so that there is a noticeable time delay from the time the first and last car is moved from re

olga nikolaevna [1]

Answer:

Without this slack, a locomotive might simply sit still and spin its wheels. The loose coupling enables a longer time for the entire train to gain momentum, requiring less force of the locomotive wheels against the track. In this way, the overall required impulse is broken into a series of smaller impulses. (This loose coupling can be very important for braking as well).

Explanation:

8 0

3 years ago

A rolling ball has an initial velocity of 1.6 meters per second. if the ball has a constant acceleration of 0.33 meters per seco

lukranit [14]

We have:

Initial velocity (u) = 1.6 m/s
Constant acceleration (a) = 0.33 m/s²
Time (t) = 3.6 sec

There are five constant acceleration equations that would help us to find the velocity:

$v=u+at$
$s=ut+ \frac{1}{2}at^2$
$s= \frac{1}{2}(u+v)t$
$v^2=u^2+2as$
$s=vt- \frac{1}{2}at^2$

Since we have $u, a, t$ and we want $v$
We will use the first formula $v=u+at$

$v=1.6+(0.33)(3.6)$
$v= 2.788$ m/s

7 0

3 years ago

A rocket has landed on planet x, which has half the radius of earth. An astronaut onboard the rocket weighs twice as much on pla

Nastasia [14]

Answer:

Option (c) u0

Explanation:

The escape velocity has a formula as:

V = √(2gR)

Where V is the escape velocity,

g is the acceleration due to gravity

R is the radius of the earth.

Now, from the question, we were told that the escape velocity for the rocket taking off from earth is u0 i.e

V(earth) = u0

V(earth) = √(2gR)

u0 = √(2gR) => For the earth

Now, let us calculate the escape velocity for the rocket taking off from planet x. This is illustrated below below:

g(planet x) = 2g (earth) => since the weight of the astronaut is twice as much on planet x as on earth

R(planet x) = 1/2 R(earth) => planet x has half the radius of earth

V(planet x) =?

Applying the formula V = √(2gR), the escape velocity on planet x is obtained as follow:

V(planet x) = √(2g(x) x R(x))

V(planet x) = √(2 x 2g x 1/2R)

V(planet x) = √(2 x g x R)

V(planet x) = √(2gR)

The expression obtained for the escape velocity on planet x i.e V(planet x) = √(2gR), is exactly the same as that obtained for the earth i.e V(earth) = √(2gR)

Therefore,

V(planet x) = V(earth) = √(2gR)

But from the question, V(earth) is u0

Therefore,

V(planet x) = V(earth) = √(2gR) = u0

So, the escape velocity on planet x is u0

4 0

3 years ago

A pillow with mass of 0.3 kg sits on a bed with a coefficient of static friction of 0.6. What is the maximum force of static fri

lys-0071 [83]

The maximum force of static friction is the product of normal force (P) and the coefficient of static friction (c). In a flat surface, normal force is equal to the weight (W) of the body.

P = W = mass x acceleration due to gravity

P = (0.3 kg) x (9.8 m/s²) = 2.94 kg m/s² = 2.94 N

Solving for the static friction force (F),
F = P x c

F = (2.94 N) x 0.6 = 1.794 N

Therefore, the maximum force of static friction is 1.794 N.

5 0

3 years ago

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One method used to determine the volume of solids and liquids is displacement.

andreyandreev [35.5K]

A. True. You can use displacement to determine the volume of solids and liquids.

4 0

3 years ago

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