Answer:
A
Explanation:
Given that a stone dropped from the top of a 80m high building strikes the ground at 40 m/s after falling for 4 seconds. The stone's potential energy with respect to the ground is equal to its kinetic energy. (use 9 - 10 m/s)
O at the moment of impact
2 seconds after the stone is released after the stone has fallen 40 m
when the stone is moving at 20 m/s
At the top of the hill, the P.E = mgh
P.E = 10 × 80 × m
P.E = 800m
At the moment of impact, K.E = 1/2mv^2
K.E = 1/2 × 40^2 × m
K.E = 1/2 × 1600 × m
K.E = 800m
Since both P.E and K.E are the same, we can therefore conclude that the stone's potential energy with respect to the ground is equal to its kinetic energy at the moment of impact.
The correct answer is option A.
The law of conservation of mass states that mass can never be created or destroyed, only changed. true or faulse
Answer:
true
Explanation:
The law of conservation of mass states that in a chemical reaction mass is neither created nor destroyed. For example, the carbon atom in coal becomes carbon dioxide when it is burned. The carbon atom changes from a solid structure to a gas but its mass does not change.
Exercise 25
1. Ablock of wood is 10 cm long, by 4 cm broad
by 15 cm thick. The block weighs 31 g.
Find the density of the wood in kg/m!
Explanation:
d=m/v. volume in cm^3 is 10x4x15=600cm^3. 31g/600cm^3 converts to .031kg/.0006m^3.
PLEASEEE HELPPP!!!
A mover slides a refrigerator weighing 650 N at a constant velocity across the floor
a distance of 8.1 m. The force of friction between the refrigerator and the floor is
230 N. If the work was done in 55 seconds, what is the power of the mover?
Given :
A mover slides a refrigerator weighing 650 N at a constant velocity across the floor a distance of 8.1 m.
The force of friction between the refrigerator and the floor is 230 N.
To Find :
How much work has been performed by the mover on the refrigerator.
Solution :
Since, refrigerator is moving with constant velocity.
So, force applied by the mover is also 230 N ( equal to force of friction ).
Now, work done in order to move the refrigerator is :
[tex]W = Force\times distance\\\\W = 230 \times 8.1\ N\ m\\\\W = 1863\ N\ m[/tex]
Hence, this is the required solution.
What is the mathematical relationship between wavelength and velocity?
Answer:A wave has a wavelength λ, which is the distance between adjacent identical parts of the wave. The wave velocity and the wavelength are related to the wave's frequency and period by vw=λT or vw=fλ.
Explanation:
Can someone explain what is force constant k in Hooke’s law
F = kx
Answer:
answer is in photo
When a 0.622 kg basketball hits the floor, its velocity changes from 4.23 m/s down to 3.85 m/s up. If the average force was 72.9 N, how much time was it in contact with the floor?
(Unit = s)
Remember: up is +, down is -
Answer:
t = 0.0689 s
Explanation:
Given that,
Mass of a basketball, m = 0.622 kg
Initial velocity, u = 4.23 m/s (downward or negative)
Final velocity, v = 3.85 m/s (up of positive)
Average force, F = 72.9 N
We need to find the time it was in contact with the floor. The force is given by :
[tex]F=ma\\\\F=m\dfrac{v-u}{t}\\\\t=\dfrac{m(v-u)}{F}\\\\t=\dfrac{0.622\times (3.85-(-4.23))}{72.9}\\\\t=0.0689\ s[/tex]
So, the time of contact is 0.0689 s.
is vibrating considered work
Answer: no it shouldn't be
Explanation:
bold completed over 100m in 9.58
seconds what is his average speed
Answer:
At the Berlin 2009 World Championships, Bolt set a world record time of 9.58 seconds for the 100m race, notching a top speed of 27.8 miles per hour (44.72 kilometers per hour) between meters 60 and 80, with an average speed of 23.5 mph.
Explanation:
A car of mass 1000 kg travelling at a velocity of 25 m/s collides with another car of mass 1500kg which is at rest. The two cars stick and move off together. What is the velocity of the two cars after the collision?
Answer:
The velocity of the two cars is 10 m/s after the collision.
Explanation:
Law Of Conservation Of Linear Momentum
The total momentum of a system of bodies is conserved unless an external force is applied to it. The formula for the momentum of a body with mass m and velocity v is
P=m.v
If we have a system of bodies, then the total momentum is the sum of them all
[tex]P=m_1v_1+m_2v_2+...+m_nv_n[/tex]
If some collision occurs, the velocities change to v' and the final momentum is:
[tex]P'=m_1v'_1+m_2v'_2+...+m_nv'_n[/tex]
In a system of two masses, the law of conservation of linear momentum takes the form:
[tex]m_1v_1+m_2v_2=m_1v'_1+m_2v'_2[/tex]
If both masses stick together after the collision at a common speed v', then:
[tex]m_1v_1+m_2v_2=(m_1+m_2)v'[/tex]
The car of mass m1=1000 Kg travels at v1=25 m/s and collides with another car of m2=1500 Kg which is at rest (v2=0).
Knowing both cars stick and move together after the collision, their velocity is found solving for v':
[tex]\displaystyle v'=\frac{m_1v_1+m_2v_2}{m_1+m_2}[/tex]
[tex]\displaystyle v'=\frac{1000*25+1500*0}{1000+1500}[/tex]
[tex]\displaystyle v'=\frac{25000}{2500}[/tex]
v' = 10 m/s
The velocity of the two cars is 10 m/s after the collision.
Please find attached photograph for your answer.
Mars orbits the Sun once
every 687 days in a circle
of radius 2.28 x 10^10 m.
What is Mars' velocity?
(Unit = m/s)
Answer:
2413
Explanation:
If your on Acellus 2413 is what you want to put in
Which type of energies make up the mechanical energy of a roller coaster moving along a track?
Answer:
gravitational potential energy and kinetic energy
Explanation:
(please awnser i need my grade up) We can calculate the about of potential energy in an object using the formula PE = mgh where m is the mass of the object, g is the acceleration due to gravity (which on Earth is a constant 9.8) and h is the height the object is from ground. If I have a 2kg bar of gold and raise that to a shelf mounted 3 meters from the ground what is that objects GPE? Remember to insert the numbers into the formula like this PE = (2) (9.8) (3) , you may use your calculator to complete this multiplication problem.
Answer:
88.2 J
Explanation: Hope I helped <3
A car tyre is pumped to a pressure of 20000 Nm-2 in the morning when the temperature is 23 oC. Later in the day, the temperature rises to 34 oC. Calculate the new pressure in the tyre. The volume is kept constant.
Answer:
20743.24 Nm¯²
Explanation:
From the question given above, the following data were obtained:
Initial pressure (P1) = 20000 Nm¯²
Initial temperature (T1) = 23 °C
Final temperature (T2) = 34 °C
Final pressure (P2) =?
Volume = constant
Next, we shall convert celsius temperature to Kelvin temperature. This can be obtained as follow:
T(K) = T(°C) + 273
Initial temperature (T1) = 23 °C
Initial temperature (T1) = 23 °C + 273 = 296 K
Final temperature (T2) = 34 °C
Final temperature (T2) = 34 °C + 273 = 307 K
Finally, we shall determine the final (i.e the new) pressure of the tyre.
Initial pressure (P1) = 20000 Nm¯²
Initial temperature (T1) = 296 K
Final temperature (T2) = 307 K
Final pressure (P2) =?
Volume = constant
Since the volume is constant, the final (i.e the new) pressure of the tyre can be obtained by using the following formula:
P1/T1 = P2/T2
20000 / 296 = P2 /307
Cross multiply
296 × P2 = 20000 × 307
Divide both side by 296
P2 = (20000 × 307) /296
P2 = 20743.24 Nm¯²
Therefore, the new pressure of the tyre is 20743.24 Nm¯²
a bicycle has a wheel with a radius of 0.75 meters. the wheel makes 12544 revolutions in 5.75 . how many radians did the wheel move ? what was the angular velocity? how far did the bicycle travel? what was the linear velocity?
Answer:
daddy went to get milk really quick.
Explanation:
he will come back ;)
A person with a mass of 75 kg is accelerated to 3m/s2 how much force applied to him
Answer:
225 NExplanation:
The force acting on an object given it's mass and acceleration can be found by using the formula
force = mass × acceleration
From the question we have
force = 75 × 3
We have the final answer as
225 NHope this helps you
PLEASE HELP ME IM TIMED
what happens when a temperature
increases.
Answer:
if the tempertaure is increase it effects us very badly. it affects not only us . it effects our whole enviroment.
What would the speed of a free-falling cell phone be exactly 0.59 seconds after it is dropped
from a student's hand (assuming no air resistance)?
Answer:
C. 5.8 m/s
Explanation:
You just need to multiply the rate of gravity, 9.8 m/s/s, by 0.59, time. You would get 5.782 so you would round it up to 5.8
The lines on the position-time graph shows the velocities of different vehicles. Which line represents a vehicle moving at a constant velocity?
A. D
B. B
C. A
D. C
How is sea salt harvested from the ocean? Name and explain the process.
Answer:
Sea salt is harvested by evaporating the ocean water away and generally has little to zero processing involved. Major sea salt manufacturers pump sea water into huge shallow “ponds” and allow the sun to evaporate the water... Before harvesting seawater, be sure the body of water you are using is not polluted.
Explanation:
hope it helps, please mark as brainliest
Near the surface of Earth, what is the acceleration of an object due to the force of gravity? !!!!! Please answer !!!!!
Answer:
Weight. Recall that the acceleration of a free-falling object near Earth's surface is approximately g=9.80m/s2 g = 9.80 m/s 2 . The force causing this acceleration is called the weight of the object, and from Newton's second law, it has the value mg.
Explanation:
Which equation below is correctly balanced?
A 2Na + O2 ---> 2Na2O
B Sn + 2KOH ---> K2SnO2 + 2H2
C AsCl3 + 3H2O ---> 3HCl + As(OH)3
D H2 + O2 ---> H2O
Answer:
D H2 + O2 ---> H2O
Explanation:
Answer:
I am not sure what the answer is but keep reading.
Explanation:
The answer is not D or A for sure
6th grade science I mark as brainliest.
Answer:
2m 13[tex]\frac{1}{3}[/tex]s
Explanation:
1.5m = 1s
200m = [tex]\frac{200}{1.5}[/tex] × 1s
= 133[tex]\frac{1}{3}[/tex]s
= 2m 13[tex]\frac{1}{3}[/tex]s
How many meters are in 22,053 kilometers? If there are 1,000 meters in one kilometer
Answer:
50m
Explanation:
What does a curved gradient line in a distance-time graph represent?
Answer:
If the line is curved, the slope is changing, which also means the velocity is changing. In a distance-time graph, the gradient of the line is equal to the speed of the object. The more the gradient (and the steeper the line) the faster the object is moving.
what is the weight of a 15 kg object
to get weight multiply Mass by 9.8
weight =9.8x15=147N
What is the average speed of a race car that moved 20 kilometers in 10 minutes?
Answer:21
Explanation:every body said
What energy transformations take place from the outlet charger to the ringing phone?
Explain how the Law of Conservation of Energy applies to the energy
transformations that occur from the outlet charger to the ringing phone.
Answer:
Chemical energy transformations take place from the outlet charger to the ringing phone.
Explanation:
chemical energy
While charging the mobile electrical energy gets transformed into chemical energy. Most of the contemporary mobile phone batteries are lithium-ion batteries where the power is saved by the chemical transformations in the ionic structure of the battery. When the power gets into the mobile phone it is transformed and collected as chemical energy inside of the battery and when we utilize the mobile the earlier saved chemical energy is again transformed into electrical energy.
The energy transformation that takes place from the outlet charger to the
ringing phone is electrical energy from the outlet is converted to chemical
energy and back to electrical energy and sound energy when the phone is
being used and ringing.
The charger provides a source of electrical energy which gets converted to
chemical energy stored in the battery. During use, the chemical energy gets
converted to electrical energy to power the phone and to sound energy
when it rings with heat energy being dissipated also.
Read more on https://brainly.com/question/2634258
I'll give brainliest!
During the last 5 million years, how often have the poles reversed
themselves?
5
20
10
15
the answer to this problem is 15
Answer:itts 20 15 is incorrect ill show u proof
Explanation:
Matter can go through a phase change and still have the same mass.
Answer:
True
Explanation:
In a physical change such as melting, can change its form but the total mass will remain the same. For example, in a chemical reaction, the total mass of substances that react will equal the mass of the products. However, it is important to mention that some phase changes such as from solid to liquid, the mass of an ice will be turned to the liquid what and during this phase change period, the mass of the ice consequently decreases.