Please help with this problem.

When riding a 10-speed bicycle up a hill, a cyclist shifts the chain to a larger-diameter gear attached to the back wheel. Why i

dimaraw [331]

To solve this problem we will use the concepts of the moment of rotational inertia, angular acceleration and the expression of angular velocity.

The rotational inertia is expressed as follows:

$I = \sum mr^2$

Here,

m = Mass of the object

r = Distance from the rotational axis

The rotational acceleration in terms of translational acceleration is

$\alpha = \frac{a}{R}$

Here,

a = Acceleration

R = Radius of the circular path of the object

The expression for the rotational speed of the object is

$\omega = \frac{\Delta \theta}{\Delta t}$

Here,

$\Delta \theta$ is the angular displacement of the object

The explanation by which when climbing a mountain uphill is changed to a larger pinion, is because it produces a greater torque but it is necessary to make more pedaling to be able to travel the same distance. Basically every turn results in less rotations of the rear wheel. Said energy that was previously used to move the rotation of the wheel is now distributed in more turns of the pedal. Therefore option a and c are correct.

This would indicate that the correct option is D.

8 0

4 years ago

If an area has limited types of wildlife, this means that it has __________. A. animals that are about to go extinct B. animals

Greeley [361]

Answer:

Explanation:

D

Maybe A

6 0

3 years ago

Read 2 more answers

A janitor standing on the top floor of a building wishes to determine the depth of the elevator shaft. They drop a rock from res

Bumek [7]

Answer:

Part a)

H = 26.8 m

Part b)

error = 7.18 %

Explanation:

Part a)

As the stone is dropped from height H then time taken by it to hit the floor is given as

$t_1 = \sqrt{\frac{2H}{g}}$

now the sound will come back to the observer in the time

$t_2 = \frac{H}{v}$

so we will have

$t_1 + t_2 = 2.42$

$\sqrt{\frac{2H}{g}} + \frac{H}{v} = 2.42$

so we have

$\sqrt{\frac{2H}{9.81}} + \frac{H}{336} = 2.42$

solve above equation for H

$H = 26.8 m$

Part b)

If sound reflection part is ignored then in that case

$H = \frac{1}{2}gt^2$

$H = \frac{1}{2}(9.81)(2.42^2)$

$H = 28.7 m$

so here percentage error in height calculation is given as

$percentage = \frac{28.7 - 26.8}{26.8} \times 100$

$percentage = 7.18$

5 0

3 years ago

A string is vibrating between two posts as shown above. Students are to determine the speed of the wave within this string. They

kow [346]

Answer:

The distance between two posts

Explanation:

As the students have already measured the amount of time necessary for the wave to oscillate up and down that is on the string between two posts,They have to measure the speed of the wave.

ie v=fλ

<em>They have to measure distance between the posts. </em>

Because wavelength is equal to the distance between the posts ie full length of string.

The frequency of the wave is calculated by

f= 1/T

Where is the time period which the students have calculated ie the amount of time taken to oscillate up and down,

Thus the wave speed is calculated using formula

v=λ/T

6 0

3 years ago

Please helppppppppp!!!!!!!!!!?

Alja [10]

Answer:

<h3><em><u>Magnesium has an atomic number of 12, which means its neutral atom has 12 electrons. The Mg2+ ion is formed when the neutral magnesium atom loses 2 electrons, which brings its total number of electrons to 10</u></em></h3>

4 0

3 years ago