What is the average speed of a human that runs a distance of 5 miles in 1 hour?

Cart 1 of mass m is traveling with speed 2vo in the +x-direction when it has an elastic collision with cart 2 of

iogann1982 [59]

Answer:

Explanation:

Momentum conservation

$m2v_0+2mv_0=mv_1+2mv_2 \quad (1/m) \quad 4v_0=v_1+2v_2\\$

Kinetic energy conservation

$\displaystyle \frac{1}{2}m(2v_0)^2+\frac{1}{2}2mv_0^2=\frac{1}{2}mv_1^2+\frac{1}{2}2mv_2^2 \quad (1/m) \quad 6v_0^2=v_1^2+2v_2^2$

Solve the system

6 0

3 years ago

What is the frequency of a microwave of wavelength 3cm?

navik [9.2K]

Frequency = (speed) / (wavelength)

Speed = 3 x 10⁸ m/s

Wavelength = 3 cm = 0.03 m

Frequency = (3 x 10⁸ m/s) / (0.03 m)

Frequency = (3 x 10⁸ / 0.03) (m / m-s)

Frequency = 1 x 10¹⁰ Hz (10 Gigahertz)

5 0

3 years ago

What is the acceleration if we speed up from 10m/s to 30 m/s in 10 seconds

lina2011 [118]

Acceleration= change in speed/ change in time

30-10= 20 (change in speed)
Time= 10 seconds

20/10= 2
Acceleration= 2 m/s^2

Hope this helps! :)

3 0

3 years ago

A dockworker loading crates on a ship finds that a 21-kg crate, initially at rest on a horizontal surface, requires a 73-N horiz

Nataliya [291]

1) Static friction coefficient: 0.355

The crate is initially at rest. The crate remains at rest until the horizontal pushing force is less than the maximum static frictional force.

The maximum static frictional force is given by

$F_s = \mu_s mg$

where

$\mu_s$ is the static coefficient of friction

m = 21 kg is the mass of the crate

g = 9.8 m/s^2 is the acceleration due to gravity

The horizontal force required to set the crate in motion is 73 N: this means that this is the value of the maximum static frictional force. So we have

$F_s=73 N$

Using this information into the previous equation, we can find the coefficient of static friction:

$\mu_s = \frac{F}{mg}=\frac{73 N}{(21 kg)(9.8 m/s^2)}=0.355$

2) Kinetic friction coefficient: 0.267

Now the crate is in motion: this means that the kinetic friction is acting on the crate, and its magnitude is

$F_k = \mu_k mg$ (1)

where

$\mu_k$ is the coefficient of kinetic friction

There is a horizontal force of

F = 55 N

pushing the crate. Moreover, the speed of the crate is constant: this means that the acceleration is zero, a = 0.

So we can write Newton's second law as

$F-F_k = ma = 0$

And by substituting (1), we can find the value of the coefficient of kinetic friction:

$F-\mu_k mg = 0\\\mu_k = \frac{F}{mg}=\frac{55 N}{(21 kg)(9.8 m/s^2)}=0.267$

5 0

3 years ago

Respond to the following based on your reading (write your answers using 1–2 paragraphs). 1. Describe the universal gravitationa

yaroslaw [1]

Answer:

Explanation:

1. Discovered by Sir Isaac Newton, this law states that every object in the universe that has mass attracts every other object in the universe that has mass. The force is proportional to the product of the two masses and inversely proportional to the square of the distance between their centers. When applying this to a situation with two objects, the object with the smaller mass will do most of the moving because the other object has too much inertia to move any noticeable amount.

2. Without advanced technology like we have today, Ptolemy and Copernicus tried to best explain the model of the universe through observation. Ptolemy’s model came first and placed a stationary earth at the center of the model. Everything else moved in respect to earth. This was widely accepted since it seemed like earth wasn’t moving. Ptolemy stated that the planetary bodies moved around earth in circular paths. However, this wasn’t always witnessed through observation. He adjusted his model to state that some planets must be moving in secondary orbits.

Copernicus put a rotating earth in a sun-centered model. The rotation of earth was able to account for the rising and setting of stars. The orbital motion of the earth and moon also accounted for the motion of the sun and moon with respect to the stars. This was easier to understand but encountered scrutiny due to its differences from religious teachings.

One big difference between the approaches in the two is that Copernicus didn’t try to adjust his model to match what was going on; he used observations to develop the model. In addition, one common trend in science is that the simplest explanation is usually most accurate or closer to accurate. Copernicus’ model was more straightforward; Ptolemy’s was more complex.

3. Acceleration in a circle is toward the center of the circle, while velocity is always a straight line that's tangent to the circle. Thus, when the boy lets go of the rope, the centripetal force (acceleration) toward the center of the circle disappears. The ball then follows the straight path, tangent to the circle, and follows Path A.

7 0

3 years ago