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Questions posted in Physics


A skier with a potential energy of 137,200 J waits on top of a ski jump that is 200 m high. What is the mass of the skier?

Physics 18/01/2020 11:31 AM answersmine

Answer:

PE = mgh

137200 = mg x 200

686 = mg

686/9.81 = m

m = 69.9286

If a 4 resistor a 7 resistor and a 12 resistor are connected in parallel which resistor had the most current in it1).42).73).124).they all have the same

Physics 18/01/2020 11:31 AM answersmine
Current is inversely proportional to resistance, ie the more resistance, the less current, so the 4 ohm resistor will have the most current

If a 100 W light bulb and a 75 W light bulb operate from 220 V the _____ bulb has a greater current in it1).75 W2). 100 W

Physics 18/01/2020 11:31 AM answersmine

Answer: The correct answer is 100 W.

Explanation:

The expression for the power in terms of voltage and the current is as follows;

P=VI                                                                    .......... (1)

Here, P is the power, V is the voltage and I is the current.

It is given in the problem that a 100 W light bulb and a 75 W light bulb operate from 220 V .

Calculate the current for light bulb, 100 W by rearranging the above expression.

Put P= 100 W and V= 220 V.

I=\frac{100}{220}

I= 0.45 A

Calculate the current for light bulb, 75 W by expression (1).

Put P= 75 W and V= 220 V.

I=\frac{75}{220}

I= 0.34 A

Therefore, 100 W light bulb has a greater current in it

20 kg object travels 28 meter and stops. coefficient friction= 0.085 how much work was done by friction?

Physics 18/01/2020 11:31 AM answersmine
Assuming it is on a horizontal surface:
friction = μR
R = 20g (g is gravity 9.81)
so Friction = 0.085 x 20g
Work done is force x distance 
so Work done = 0.085 x 20g x 28
 = 466.956 J

A pitcher throws a softball toward home plate. When the ball hits the catcher’s mitt, its horizontal velocity is 32 meters/second. The softball’s velocity goes to 0 meters/second in 0.8 seconds when caught. If the softball has a mass of 0.2 kilograms, what’s the force of the impact? Use F = ma, where . The force of the impact is newtons.

Physics 18/01/2020 11:26 AM answersmine
Answer
8 Newtons

Explanation
The first step is to calculate the acceleration (a) of the ball.
 
a = (v-u)/t
where a⇒acceleration
           v ⇒final velocity = 0 m/s
           u ⇒initial velocity =32 m/s

∴a = (0 - 32)/0.8
     = -40m/s² 
The acceleration is negative indication the softball was decelerating. 

Now force of impact;

F = ma
where m⇒ mass of the softball in kilogram

F = 0.2×-40
   = -8

But force can not be negative,
So, impact force =8 Newtons

If the amount of CFCs in the atmosphere decrease, then..?

Physics 18/01/2020 11:26 AM answersmine
If the amount of CFCs in the atmosphere decrease then the 'hole' above Antarctica will get smaller and smaller. 

A 100-meter sprint is a race using only the straight side of a racetrack. A 400-meter sprint is a race that makes one complete lap around a racetrack. Why are velocity and speed the same for 100-meters sprint but not a 400-m sprint?

Physics 18/01/2020 11:26 AM answersmine
Velocity is a vector quantity and depends on both speed and direction.
In 100m you only travel straight in one direction.
But in 400m you have to turn corners and then go back the way you came, and then turn another corner, you're changing direction - hence changing velocity, even if the speed is the same.

What is denser a iron sheet or iron powder??

Physics 18/01/2020 11:25 AM answersmine
Iron sheet because the molecules are more condense.
I guess Im Not sure

Atoms become charged by gaining or losing ______.1). electrons2). protons3). neutrons

Physics 18/01/2020 11:25 AM answersmine
Electrons
eg;;;;;; when enough electrons are added so that there are more electrons than protons, the atom becomes a negatively charged ion

An unknown noise is generated in a building. Sound waves move toward an open doorway. Waves of which wavelength would diffract the least through the doorway and spread into the room? 15 centimeters 1 meter 5 meters 12.5 meters

Physics 18/01/2020 11:22 AM answersmine

The correct choice is

15 centimeters

The diffraction of the sound waves takes place when the wavelength of sound wave is comparable with the size of the object. Waves of wavelengths 1 meter, 5 meter, and 12.5 meters are comparable to the size of the doorway while the wavelength 15 centimeters is very small compared to the size of the doorway. hence the waves of wavelength 15 cm diffracts the least.

A 9 V battery sends a current of 0.5 A through a resistor. What is the value of the resistance?

Physics 18/01/2020 11:21 AM answersmine
V = IR
V/I = R
9/0.5 = R
R = 18 ohms

How could we expect a white paper to appear when viewed in a red light?

Physics 18/01/2020 11:17 AM answersmine
The accurate answer is:
You could expect a white paper to have a red tone when viewed in a red light. This is the case because of the neutrality of the white paper.

Which of the following pieces of laboratory equipment is not directly used to make measurements a.test tube b.graduated cylinder c.ruler d.thermometer

Physics 18/01/2020 11:16 AM answersmine

Answer:

A. Test tube.

Explanation:

The test tubes are used to collect samples of a particular liquid.

A graduated cylinder is like a test tube but it has marks on the tube to measure the volume of a liquid.

A ruler is used to measure length.

And finally, a thermometer is used to measure the temperature.

I hope this answer helps you.

How do the lights in a series circuit behave when one bulb turns out

Physics 18/01/2020 11:12 AM answersmine

The rest of the bulbs stop shining and shut off.

W=4j, d=2m,and F=10N find cosine

Physics 18/01/2020 11:12 AM answersmine
Correct your answer to the amount of significant figures the questions wants

An area of wave-washed sediment along a coast is called a __________. barrier beach sandbar headland beach

Physics 18/01/2020 11:11 AM answersmine

The correct answer is BEACH. I just finished the assignment and that's the correct answer.

Antacids contain bases that react with the acid in your stomach to relieve indigestion. In the reaction below, NaHCO3 reacts with HCl to form a salt, CO2, and H2O. This type of reaction is called ____. NaHCO3(s) + HCl(aq) ---> NaCl(s) + CO2(g) + H2O(l) Select one: a. neutralization b. dehydration c. titration d. oxidation

Physics 18/01/2020 11:10 AM answersmine

The answer is A.  Neuralization occurs when a base is mixed with an acid and the general equation is;

acid + base(alkali) → salt + water

Another application of neutralization, other than its application in antiacids, is its use in fertilizer to bring bask coils pH to the required standard for optimum growth of plants.






If you are running at the speed of sound, would you still be able to hear the music in your headphones?

Physics 18/01/2020 11:10 AM answersmine
Ask Barry Allen he’s the faster man alive

Which coefficient of O2 is needed to balance the equation C3H8 + O2 → 3CO2 + 4H2O? 2 3 5 6

Physics 18/01/2020 11:06 AM answersmine
The answer would be 5.

Equation = C3 H8 + O2 → Co2 + H2O
Balanced equation = 
C3H8 + O2 → 3CO2 + 4H2O
In the first part, left side, has 2 oxygens, and the next one has 10. So in order to turn 2 into 10, add the coefficient 5.

A car traveling at 27 m/s starts to decelerate steadily. It comes to a complete stop in 14 seconds. What is its acceleration?

Physics 18/01/2020 11:02 AM answersmine
You will need to use this formula:

V = Vo + a x t

V - Final velocity // If it comes to a complete stop,it will be 0 m/s.
Vo - Initial velocity = 27 m/s
a - Acceleration = ? m/s^2 // All units are in S.I
t - Time = 14 secs

So:

-> 0 = 27 + a x 14
-> 14a + 27 = 0
-> 14a = -27
-> a = -27/14
-> a = -1.928... m/s^2

Rounding to the nearest hundredth: -1.93 m/s^2.

Answer: The acceleration of the car is -1.93 m/s^2.

A train travels 98 kilometers in 4 hours, and then 61 kilometers in 3 hours. What is its average speed?

Physics 18/01/2020 11:01 AM answersmine
Speed (velocity)=distance/time

V1=98km/4hr=24.5km/hr
V2=61km/3hr=20.3km/hr

Average speed (velocity)=total velocity/ number

Average speed (velocity)=44.8km/hr/2=22.4

So the average speed is 22.4km/hr