A woman lifts a 300 newton child a distance of 1.5 meters in 0.75 seconds. What is her power output in lifting the child?

QUESTION POSTED AT 13/11/2019 - 05:21 PM

Answered by admin AT 13/11/2019 - 05:21 PM

Power = Work done / time

Work done = Force * Distance
                 =  300 N *  1.5 m =  450 J

Power =  450 / 0.75 = 600 Watts.
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_____ energy powers the water cycle. Geothermal Solar Latent Electric

B) Solar
Water cycle is driven primarily by the energy from the sun.

ANSWERED AT 15/12/2019 - 11:04 PM


QUESTION POSTED AT 15/12/2019 - 11:04 PM

The _____ of the Sun has a temperature of about 15 million Celsius. photosphere corona core radiative zone chromosphere convective zone

The core of the Sun has a temperature of about 15 million Celsius.

ANSWERED AT 15/12/2019 - 10:52 PM


QUESTION POSTED AT 15/12/2019 - 10:52 PM

Describe the relative amounts of potential and kinetic energy for a book in the following situations. a. the book on a high shelf which is 2 meters of the ground. b. the book after it has fallen off a 2-meter shelf and is now 1-meter of the ground. c. the book just before it hits the ground.

A) The book has gravitational potential potential energy equal to m x g x h = 19,6 x m where m is the mass of the book. As the book is stationary, it has zero kinetic energy.
b) As the book falls, its potential energy decreases and is converted to its kinetic energy in the process, which increases. At a distance of about 1m from the ground, its potential energy is equal to its kinetic energy that is 9.8 x m where m is the mass of the book.
c) Just before the book hits the ground, it has maximum kinetic energy that is equal to its potential energy in part a). As its height from the ground is 0, its potential energy is zero is at this point.

ANSWERED AT 15/12/2019 - 10:47 PM


QUESTION POSTED AT 15/12/2019 - 10:47 PM

Give an order of magnitude estimate of the number of seconds in the life of a dog.

The average dog lifespan is 12 years. The number of seconds is 12 x 60 x 60 = 43,200 s which is of the order 4 x 10^4s

ANSWERED AT 15/12/2019 - 10:47 PM


QUESTION POSTED AT 15/12/2019 - 10:47 PM

Speed is the ratio of the distance an object moves to (1 point)the amount of time needed to travel the distance. the direction the object moves. the displacement of the object. the motion of the object.

A) the distance an object moves to the amount of time needed to travel the distance.
Speed is the rate of change of distance with time.

ANSWERED AT 15/12/2019 - 10:13 PM


QUESTION POSTED AT 15/12/2019 - 10:13 PM

What would happen if an automobile moving at a high speed suddenly comes to a stop? How does this relate to Newton's laws and what factors could change the effect of the sudden stop on the passengers?

If an automobile moving at high speed suddenly comes to a stop, you would have a large change in momentum. This relates to Newton's second law in the form F = delta p / delta t, where p is momentum (mv).
You could lessen the effect of the sudden stop on the passengers by changing the average force exerted on them. If you look at Newton's second law again, you can see that given some delta p, you can decrease F by increasing delta t. What this means is that if you increase the length of time over which the change in momentum occurs, you can decrease the average force exerted to obtain that change in momentum. This is the reason why landing on a soft cushion is preferable to landing on a concrete surface. The cushion gives way to any object falling on it while still providing some resistance (you don't stop as abruptly), so while your change in momentum is the same in both cases, you have a larger delta t in the case of the cushion.

ANSWERED AT 15/12/2019 - 10:12 PM


QUESTION POSTED AT 15/12/2019 - 10:12 PM

Is the second largest planet, with an atmosphere of mainly hydrogen and helium, and rings of ice and rock particles

Answer:

Saturn

Explanation:

There are 8 planets in the solar system. The smallest planet is mercury where as the largest planet is Jupiter. The second largest planet is Saturn. It is a Jovian planet composed of gases mainly hydrogen and helium. It is known for its beautiful ring system which are even visible when viewed from the earth. The rings are made of ice and rock. It is the lightest planet, its density being even lower than that of water.

ANSWERED AT 15/12/2019 - 09:46 PM


QUESTION POSTED AT 15/12/2019 - 09:46 PM

When measuring the distance between two objects to find universal gravitation where must you measure from?


The distance is measured between the 'centers of mass',
or 'centers of gravity' of both objects.  That's the point inside
the object where there's the same amount of mass in every
direction away from it.

If the object is something like a sphere, or a cube, or a uniform
wooden board, or anything "symmetrical", then the center of mass /
center of gravity is the actual center of the object.  If the object has
some irregular shape, then it's harder to calculate or measure where
its center is.



ANSWERED AT 15/12/2019 - 09:39 PM


QUESTION POSTED AT 15/12/2019 - 09:39 PM

The formula d = rt gives the distance d traveled in time t at rate r. A train travels 163.2 miles in 2.4 hours, traveling at a constant rate. What is the train s rate of travel?

Since d= 163.2 and t = 2.4, we divide 163.2 by 2.4 to get 68 miles per hour.

ANSWERED AT 15/12/2019 - 09:27 PM


QUESTION POSTED AT 15/12/2019 - 09:27 PM

The Axis powers were made up of coalition of countries that opposed the powers in World War II.

The Axis forces in World War II were considered to be the bad guys from a historical perspective, the Axis forces composed of Hitler's Germany, Italy and Japan. These were the three major axis forces.

ANSWERED AT 15/12/2019 - 06:17 PM


QUESTION POSTED AT 15/12/2019 - 06:17 PM

Your friend, who is age 15 and has a resting heart rate of 70, wishes to start a jogging program. What would you suggest as a proper starting target heart rate? 138 115 178 155

Actually its 155, got this wrong on my test when I put 138 :)

ANSWERED AT 15/12/2019 - 06:10 PM


QUESTION POSTED AT 15/12/2019 - 06:10 PM

Klint and Matt decided to race go-Karts down the hill at their house. The mass of Matt's go-Kart is 86kg. Klint's cart falls apart halfway down the hill. Matt's go-cart makes it all the way to the bottom in 40 seconds. If the total distance of the hill is 80 feet, what is the acceleration of his go-cart?


All we can say from the given information is that Matt's
average speed from the top to the bottom is

                (80 feet) / (40 seconds)  =  2 feet per second .

We're not told whether his acceleration was constant
all the way down.  IF it was, then we could use

                               Distance = (1/2 acceleration) x (time²).

                                      80 ft  =  (1/2 acceleration) x (40 sec)²

Divide each side
by 1600 sec² :             80 ft / 1600 sec² = 1/2 acceleration

Multiply each side
by  2:                           160 ft / 1600 sec² =        acceleration

                                            Acceleration  =  0.1 ft/sec² .   
             

ANSWERED AT 15/12/2019 - 06:10 PM


QUESTION POSTED AT 15/12/2019 - 06:10 PM

If the potential energy of a box is 600 joules because it is stored on a shelf at a position of 4 meters, what is the object's mass?

Potential energy = mass x g x height. So 600 J = mass x 9.81 m/s^2 x 4m, mass = 600 J/ (9.81 m/s^2 x 4m) = 600 J/39.24 m^2/s^2 = 15.3 kg

ANSWERED AT 15/12/2019 - 06:08 PM


QUESTION POSTED AT 15/12/2019 - 06:08 PM

What is the frequency of an ultrasound that vibrates 30 000 times a second

Frequency = oscilations/vibrations per second
So the frequency is 30 000 Hz

ANSWERED AT 15/12/2019 - 06:04 PM


QUESTION POSTED AT 15/12/2019 - 06:04 PM

I have three questions. John has to hit a bottle with a ball to win a prize. He throws a 0.4 kg ball with a velocity of 18 m/s. It hits a 0.2 kg bottle, and the bottle flies forward at 25 m/s. How fast is the ball traveling after hitting the bottle? 2. Someone fires a 0.04 kg bullet at a block of wood that has a mass of 0.5 kg. (The block of woof is sitting on a frictionless surface, so it moves freely when the bullet hits it). The wood block is initially at rest. The bullet is traveling 300 m/s when it hits the wood block and sticks inside it. Now the bullet and the woof block move together as one object. How fast are they traveling? 3. A big league hitter attacks a fastball. The ball has a mass of 0.16 kg. It is pitched at 38 m/s. After the player hits the ball, it is now traveling 44 m/s in the opposite direction. The impact lasted 0.002 seconds. How big of a force did the ballplayer put on that ball?

1. 5.5 m/s

We can solve the problem by applying the law of conservation of momentum. The total momentum before the collision must be equal to the total momentum after the collision, so we have:

m_1 u_1 + m_2 u_2 = m_1 v_1 + m_2 v_2

where

m1 = 0.4 kg is the mass of the ball

u1 = 18 m/s is the initial velocity of the ball

m2 = 0.2 kg is the mass of the bottle

u2 = 0 is the initial velocity of the bottle (which is initially at rest)

v1 = ? is the final velocity of the ball

v2 = 25 m/s is the final velocity of the bottle

Substituting and re-arranging the equation, we can find the final velocity of the ball:

v_1 = \frac{m_1 u_1 - m_2 v_2}{m_1}=\frac{(0.4 kg)(18m/s)-(0.2 kg)(25 m/s)}{0.4 kg}=5.5 m/s


2. 22.2 m/s

We can solve the problem again by using the law of conservation of momentum; the only difference in this case is that the bullet and the block, after the collision, travel together at the same speed v. So we can write:

m_1 u_1 + m_2 u_2 = (m_1 +m_2) v

where

m1 = 0.04 kg is the mass of the bullet

u1 = 300 m/s is the initial velocity of the bullet

m2 = 0.5 kg is the mass of the block

u2 = 0 is the initial velocity of the block (which is initially at rest)

v = ? is the final velocity of the bullet+block, which stick and travel together

Substituting and re-arranging the equation, we can find the final velocity of bullet+block:

\frac{m_1 u_1}{m_1 +m_2}=\frac{(0.04 kg)(300 m/s)}{0.04 kg+0.5 kg}=22.2 m/s


3. 6560 N

The impulse exerted on the ball is equal to its change in momentum:

I=\Delta p (1)

The impulse can be rewritten as product between force and time of collision:

I=F \Delta t

while the change in momentum of the ball is equal to the product between its mass and the change in velocity:

\Delta p = m\Delta v = m(v_f -v_i)

So, eq.(1) becomes

F \Delta t = m(v_f -v_i)

where:

F = ? is the unknown force

\Delta t = 0.002 s is the duration of the impact

m = 0.16 kg is the mass of the ball

v_f = 44 m/s is the final velocity of the ball

v_i = -38 m/s is its initial velocity (we must add a negative sign, since it is in opposite direction to the final velocity)

So, by using the equation, we can find the force:

F=\frac{m (v_f -v_i)}{\Delta t}=\frac{(0.16 kg)(44 m/s-(-38 m/s))}{0.002 s}=6560 N

ANSWERED AT 15/12/2019 - 05:16 PM


QUESTION POSTED AT 15/12/2019 - 05:16 PM

Why is the gravitational potential energy of an object 1 meter above the moons surface less than its potential energy 1meter above earths surface? a. the objects mass is less on the moon b. the objects weight is more on the moon c. the objects acceleration due to gravity is less on the moon d. both a and c

C. the object's acceleration due to gravity is less on the moon
G = GM/r^2 where M is the mass of the body and r is the distance from the body to the point where g is being calculated. As the mass of the moon is much less than that of the earth, the acceleration due to gravity, g, is less on the moon. 

ANSWERED AT 15/12/2019 - 04:12 PM


QUESTION POSTED AT 15/12/2019 - 04:12 PM

What is the name of science created from Newtons work?

Newtonian mechanics. IT is the system of mechanics which relies on Newton's laws of motion concerning the relations between forces acting and motions occurring.

ANSWERED AT 15/12/2019 - 04:01 PM


QUESTION POSTED AT 15/12/2019 - 04:01 PM

Which of the following questions would be answered using concepts from chemistry? A. How much energy is required to lift a crate into a truck? B. How fast will a sled be moving when it reaches the bottom of a hill? C. What atoms make up water? D. How much force is required to throw a ball over a fence?

The answer is part c that is What atoms make up water?


This is because all of the option A, B and D require some sort of Physics to explain.


Such as how much energy is required, How fast or slow will something reach or how much force required on some object.


But option C, it just requires chemistry concepts as it is about the study of atoms and the usage of periodic table using covalent bonding.

ANSWERED AT 15/12/2019 - 04:01 PM


QUESTION POSTED AT 15/12/2019 - 04:01 PM

If the distance from a converging lens to the object is less than the focal length of the lens, the image will be what?

The image will be a virtual image. Using the lens equation:  \frac{1}{o} +  \frac{1}{i} =  \frac{1}{f} 
 where o is the obejct distance, i the image distance and f the focal length, and rearranging the equation we have:
 \frac{1}{i} =  \frac{1}{f} - \frac{1}{o}
So if o is less than f, i is negative, that is the image displacement is negative, it is formed behind the lens and it is a virtual image.

ANSWERED AT 15/12/2019 - 03:56 PM


QUESTION POSTED AT 15/12/2019 - 03:56 PM

A satellite is orbiting Earth in an approximately circular path. It completes one revolution each day (86,400 seconds). Its orbital distance is 22,500 kilometers from the Earth's center. What is the satellite's average speed?


For each revolution, the satellite covers the circumference
of its orbit.

The circumference of a circle is    (pi) x (diameter).

Since the satellite is 22,500 miles from the center, that number
is the radius of the circle.  The diameter is  45,000 miles.

The circumference is    (pi) x (45,000 miles) = 141,372 miles
                                                                        
The satellite's average speed is  141,372 miles per day, or

       (141,372 / 24) = 5,890 miles per hour

relative to the center of the Earth.



ANSWERED AT 15/12/2019 - 03:41 PM


QUESTION POSTED AT 15/12/2019 - 03:41 PM

A water wave has a speed of 23.0 meters/second. If the wave’s frequency is 0.0680 hertz, what is the wavelength? A)310 meters B)338 meters C)120 meters D)416 meters

Answer: Option (B) is the correct answer.

Explanation:

Given data is as follows.

Frequency = 0.0680 hertz = 0.0680 per second

Speed or velocity = 23.0 m/s

We can calculate the wavelength with the help of formula as follows.

                            v = \lambda f

                            \lambda = \frac{v}{f}

                                    = \frac{23.0 m/s}{0.0680 s^{-1}}

                                    = 338.23 meters

or,                                 = 338 meters (approx)

Thus, we can conclude that wavelength is 338 meters (approx).

ANSWERED AT 15/12/2019 - 03:32 PM


QUESTION POSTED AT 15/12/2019 - 03:32 PM

An electric heater uses 3/ 5 watts of power each hour. How many watts of power will the heater use in 1/ 2 hour? a. 3/10 b. 11/10 c. 3/5 d. 11/5


This question could not come from any school source.  If it did,
then you should always be suspicious of anything that comes
from that source.  The question contains a fundamental mistake,
and misleads the student.

"Power", measured in "watts", is a rate, not a quantity.  It tells
how fast you're using energy.  You don't use some watts this
morning and some more watts this afternoon.  That's like saying
that you'll drive some miles per hour today, and then you'll drive
some more miles per hour tomorrow.  It doesn't work that way.

The heater doesn't use up some amount of watts.  It uses up
some amount of energy.  "Watts" is the measure of how fast
or slowly it uses up the energy.

This question makes sense if you get rid of the 'watts' and call it
'pints of milk' instead.

           "My cats drink 3/5 pint of milk each hour. 
            How many pints of milk will they drink in 1/2 hour ?"

               (1/2 hour) x (3/5  pint/hour)

           =  ( 1/2  x  3/5)  (pint)

           =        3/10  pint .
 

ANSWERED AT 15/12/2019 - 03:21 PM


QUESTION POSTED AT 15/12/2019 - 03:21 PM

What is the average speed of a car that traveled 300 miles in 5.5 hrs? turn your answer from km/hr to km/min.

Convert first the unit of their distances and their time.
Since 1 mile = 1.60934 km, then
300 miles * (1.60934 km / 1 mile) = 482.802 km

Since 1 hour = 60 minutes, then
5.5 hrs * (60 min / 1 hr) = 330 minutes

The speed is distance over time.
482.802 km / 330 minutes = 1.463 km/hr

Hope this helps  ☺️ ✌️ 

ANSWERED AT 15/12/2019 - 03:13 PM


QUESTION POSTED AT 15/12/2019 - 03:13 PM

A snail can move approximately 0.30 meters per minute.How many meters can the snail cover in 15 minutes ?

Sometimes if you have the word per, you need to multiply. In this problem, they are asking you to find the amount of meters a snail can travel per minute.They are giving you the amount of minutes, so in this case you multiply 15 times 0.30. The answer is 4.5 meters.

ANSWERED AT 15/12/2019 - 03:08 PM


QUESTION POSTED AT 15/12/2019 - 03:08 PM

1. Joey drives his Skidoo 7 kilometres north. He stops for lunch and then drives 5 kilometres east. What distance did he cover? What was his displacement?

Distance he covered = (7+5)km = 12 km
His displacement =  \sqrt{7^{2}+ 5^{2}  } = 8.6 km in the north-east direction.

ANSWERED AT 15/12/2019 - 02:37 PM


QUESTION POSTED AT 15/12/2019 - 02:37 PM

The main difference between speed and velocity involves A. gravity. B. weight. C. distance. D. direction.

D. direction
Velocity tells the speed of the object together with its direction whereas speed just tells how fast the object is travelling, it is the rate of change of distance per time, and does not give any information about the direction of travel.

ANSWERED AT 15/12/2019 - 02:32 PM


QUESTION POSTED AT 15/12/2019 - 02:32 PM