PHYSICS COLLEGE

On a hot summer day in the state of Washington while kayaking, I saw several swimmers jump from a railroad bridge into the Snohomish River below. The swimmers stepped off the bridge, and I estimated that they hit the water 2.00 s later. A)How high was the bridge?B)How fast were the swimmers moving when they hit the water?

C)What would the swimmer's drop time be if the bridge were twice as high?

Answers

Answer 1

Answer:

Answer: part a: 19.62m

part b: 19.62 m/s

part a: 2.83 secs

Explanation:If the air resistance is ignored then the swimmer experience free fall under gravity hence

u=0

a=9.81 m/s2

t=2 secs

$s=ut+0.5at^2$

s=h

$h=0*2+0.5*9.81*2^2\nh=19.62 meters$

Part b

$v=u+at\nv=0+9.81*2\nv=19.62m/s$

Part c

now we have h=2*19.62=39.24

$39.24=0+0.5*9.81*t^2\nt^2=8\nt=2.83 secs$

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Trevor and Nick are taxi drivers. Trevor drives a taxi using diesel oil while Nick drives a taxi using LPG. Whose taxi will cause higher levels of air pollution and why?

Answers

Answer:

Trevor's taxi would cause higher levels of air pollution

Explanation:

Trevor's taxi use diesel oil.

Diesel is less cleaner than LPG.

Compared to automotive pollution from petrol and diesel, pollutants from LPG-driven cars include lower amounts of petroleum hydrocarbons, nitrogen oxides , sulphur oxides, ozone contamination and particulate matter.

Two small objects each with a net charge of +Q exert a force of magnitude F on each other. We replace one of the objects with another whose net charge is + 4Q. We move the +Q and +4Q charges to be 3 times as far apart as they were. What is the magnitude of the force on the +4Q charge ?A. F

B. 4F

C. 4F/3

D. 4F/9

E. F/3

Answers

Answer:

F'= 4F/9

Explanation:

Two small objects each with a net charge of +Q exert a force of magnitude F on each other. If r is the distance between them, then the force is given by :

$F=(kQ^2)/(r^2)$ ...(1)

Now, if one of the objects with another whose net charge is + 4Q is replaced and also the distance between +Q and +4Q charges is increased 3 times as far apart as they were. New force is given by :

$F'=(kQ* 4Q)/((3r)^2)\n\nF'=(4kQ^2)/(9r^2)$ .....(2)

Dividing equation (1) and (2), we get :

$(F)/(F')=((kQ^2)/(r^2))/((4kQ^2)/(9r^2))\n\n(F)/(F')=(kQ^2)/(r^2)* (9r^2)/(4kQ^2)\n\n(F)/(F')=(9)/(4)\n\nF'=(4F)/(9)$

Hence, the correct option is (d) i.e. " 4F/9"

Final answer:

The magnitude of the force on the +4Q charge, after replacing one of the original +Q charges and moving the charges three times farther apart, is calculated to be 4F/9 using Coulomb's Law. Therefore, the correct answer is D.

Explanation:

The magnitude of the electrostatic force between two charges can be described by Coulomb's Law, which states that F = k × (q1 × q2) / r^2, where F is the force between the charges, k is Coulomb's constant, q1 and q2 are the magnitudes of the charges, and r is the distance between the centers of the two charges. Originally, two objects each with charge +Q exert a force of magnitude F on each other. After one charge is replaced with a +4Q charge and they are moved to be three times as far apart, the force on the +4Q charge can be calculated using the modified version of Coulomb's Law that takes into account the new charges and distance.

Using the original scenario as a reference, where F = k × (Q × Q) / r^2, when the charge is replaced and the distance is tripled, the new force F' = k × (Q × 4Q) / (3r)^2 = 4kQ^2 / 9r^2. By comparing F' with F, we find that F' = (4/9)F. Thus, the magnitude of the force on the +4Q charge is 4F/9.

How does the mass of an object affect its motion through the air?

Answers

The motion of an object through the air does not affect by its mass. The rate of fall of objects does not depend upon the mass.

What are free fall and air resistance?

Free fall is a motion of a body in which gravity is the only force acting upon it. An object moving upwards might not be considered to be falling. But if the object is under the effect of the force of gravity, it is said to be in free fall.

Free fall is a type of motion in which the force acting upon an object is only gravity. Objects are not encountering a significant force of airresistance as they are only falling under the sole influence of gravity. All objects under such conditions will fall with the same rate of acceleration, regardless of their masses.

As an object falls through the air, have gone through some degree of air resistance. Air resistance is the collisions of the object's leading surface with molecules present in the air. The two most common factors that have a direct effect on the amount of air resistance are the cross-sectional area of the object and the speed of the object.

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Mass does not affect the speed of falling objects assuming there is only gravity acting on it. For example Both Bullets will strike the ground at the same time. The horizontal force applied does not affect the downward motion of the bullets — only gravity and friction (air resistance), which is the same for both bullets
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The gravitational force law, deduced by Newton in the 1660's, is remarkably similar to Coulomb's law. Recall that the universal law of gravitation states that the magnitude of the gravitational force between two masses M1 and M2 separated by a distance R is given by the following equation:________. F = G (M1 x M2) / R2
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a. Calculate the value of the gravitational force between an electron (mass = 9.11 x 10-31 kg) and a proton (mass is 1836 times greater than the mass of an electron) if the two particles are separated by 3.602 nanometers. (1 nanometer or 1 nm = 1 x 10-9 m)
F= ______ N
b. The force created in the above question is:
1. repulsive
2. attractive

Answers

Answer:

a. $F=7.83* 10^(-51) N$

b.Attractive

Explanation:

We are given that

$F=(GM_1M_2)/(R^2)$

$G=6.67* 10^(-11) Nm^2/kg^2$

Mass of an electron, $M_1=9.11* 10^(-31) kg$

Mass of proton, $M_2=1836* 9.11* 10^(-31) kg$

Distance between electron and proton,R= $3.602nm=3.602* 10^(-9) m$

$1nm=10^(-9) m$

a.Substitute the values then we get

$F=(6.67* 10^(-11)* 9.11* 10^(-31)* 1836* 9.11* 10^(-31))/((3.602* 10^(-9))^2)$

$F=7.83* 10^(-51) N$

b.We know that like charges repel to each other and unlike charges attract to each other.

Proton and electron are unlike charges therefore, the force between proton and electron is attractive.

A positively charged rod is held near a neutral conducting sphere as illustrated below. A positively charged particle is moved from point A to point B. Thee electrostatic work done on the positively charged particle during the motio

Answers

The movement of a positively charged particle from point A to point B. the motion-induced electrostatic work done on the positively charged particle.

Whether positively or negatively charged, an object that is neutral will interact with it in a pleasing way. Both positively charged and neutral items attract one another, as do negatively charged and neutral objects. These electrons gather on the further surface of sphere B, depleting the electron supply in sphere A. Therefore, sphere A (which is closer to the rod) obtains a positive charge and sphere B acquires a negative charge when the two spheres separate in the presence of the rod. The change in the particle's electrostatic potential energy in the external field equals the work done by the external force. When a charge is pushed from point A to point B, its potential energy changes, representing the labor of an outside force.

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We know that there is a relationship between work and mechanical energy change. Whenever work is done upon an object by an external force (or non-conservative force), there will be a change in the total mechanical energy of the object. If only internal forces are doing work then there is no change in the total amount of mechanical energy. The total mechanical energy is said to be conserved. Think of a real-life situation where we make use of this conservation of mechanical energy (where we can neglect external forces for the most part). Describe your example and speak to both the kinetic and potential energy of the motion.

Answers

Answer:

* roller skates and ice skates.

* roller coaster

Explanation:

One of the best examples for this situation is when we are skating, in the initial part we must create work with a force, it compensates to move, after this the external force stops working and we continue movements with kinetic energy, if there are some ramps, we can going up, where the kinetic energy is transformed into potential energy and when going down again it is transformed into kinetic energy. This is true for both roller skates and ice skates.

Another example is the roller coaster, in this case the motor creates work to increase the energy of the car by raising it, when it reaches the top the motor is disconnected, and all the movement is carried out with changes in kinetic and potential energy. In the upper part the energy is almost all potential, it only has the kinetic energy necessary to continue the movement and in the lower part it is all kinetic; At the end of the tour, the brakes are applied that bring about the non-conservative forces that decrease the mechanical energy, transforming it into heat.

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