Answer:
The time taken is 1.76 s.
Explanation:
mass of student, m = 45 kg
height, h = 6 m
power, P = 1500 W
Power is defined as the rate of doing work.
Work done in moving height is
W = m g h
Let the time is t.
P = m g h / t
1500 = 45 x 9.8 x 6 / t
t = 1.76 s
what can be done to increase speed of rotation of a DC motor
Answer: There are multiple options:
By varying the supply voltage.
By varying the flux, and by varying the current through the field winding.
By varying the armature voltage, and by varying the armature resistance.
Helpful Link:
https://www.elprocus.com/what-are-the-best-ways-to-control-the-speed-of-dc-motor/
một hòn đá có khối lượng 5kg bay với vận tốc 72kg/h . động lượng của hòn đá là
Answer:
Momentum = 100 Kgm/s
Explanation:
Given the following data;
Speed = 72 km/h
Mass = 5 kg
To find the momentum of the stone;
First of all, we would have to convert the value of speed to meter per seconds.
Conversion:
72 km/h to m/s = (72 * 1000)/3600 = 20 m/s
Momentum can be defined as the multiplication (product) of the mass possessed by an object and its velocity. Momentum is considered to be a vector quantity because it has both magnitude and direction.
Mathematically, momentum is given by the formula;
Momentum = mass * velocity
Substituting the values into the formula, we have;
Momentum = 5 * 20
Momentum = 100 Kgm/s
; (b) A uniform beam 150cm long weighs 3.5kg and
supported on knife-edges at its ends. The beam
supports a weight 7kg at a distance 30cm from
one end. Find the reactions of the supports.
Explanation:
(b) A uniform beam 150cm long weighs 3.5kg and
supported on knife-edges at its ends. The beam
supports a weight 7kg at a distance 30cm from
one end. Find the reactions of the supports.
three letters (JET) are placed in front of a plane mirror the image formed is in what arrangement???
Answer:
TEJ as this is a thing you wont get
GUYS PLEASE HELP ME THIS IS FOR MY FINAL !!!
Answer:
just add co-ratios and then find the average.
Explanation:
HELP ME
Which two changes to the can opener would increase its mechanical efficiency?
A shorten the paddle so that they are closer in size to the axle that they turn
B grease the rotating wheel of the opener so that there is less breaks in between moving parts
C replaced it with a straight handle the act as levers with shorter pieces of metal
D sand the cutting surface of the metal piece so that it is perfectly smooth and sharp
Answer:
I THINK IT'S D....
HOPE SO
3. There is a bell at the top of a tower that is 45 m high. The bell weighs 64 kg. The
bell has joules of potential energy.
Answer:It has 8550 j energy
what is the relation between centre of gravity and stability
Explanation:
tilting it will raise the height of its center of gravity.
A car travels initially at 24 m/s, until it enters the highway. If the car accelerates at 4 m/s^2 for a 96 meters, what is the car's new velocity?
Using 3rd equation of kinematics
[tex]\boxed{\Large{\sf v^2-u^2=2as}}[/tex]
[tex]\\ \Large\sf\longmapsto v^2=u^2+2as[/tex]
[tex]\\ \Large\sf\longmapsto v^2=24^2+2(4)(96)[/tex]
[tex]\\ \Large\sf\longmapsto v^2=576+768[/tex]
[tex]\\ \Large\sf\longmapsto v^2=1344[/tex]
[tex]\\ \Large\sf\longmapsto v=\sqrt{1344}[/tex]
[tex]\\ \Large\sf\longmapsto v=36.6m/s[/tex]
resistances is inversely proprtional to___of the conductor
Answer:
resistances is inversely proportional to the area of cross section of the conductor
Explanation:
The resistance of a wire is directly proportional to its length and inversely proportional to its cross-sectional area.
hope this helps you
have a nice day:)
Which device is used to measure the weight of a body?
Answer:
The beam balance is a device used for the determination of the mass of a body under gravitation. Beam balance is used for high precision measurements like masses up to 250g, it consists of a pair of scale pans one at each end of a rigid beam.
we use a scale to measure the weight of our bodies
write down any 5 example of conservation of momentum?
Answer:
1) Motion of air mass moving from equator northward (closer to earth axis)
2) Motion of object in orbit
3) Collision of 2 objects
4) Skater changing rotation by extension of arms
5) Motion of rocket due to velocity of expelled gas
. A radio station transmitting at a frequency of 200KH, emits waves of wavelength 1.5 km.the velocity of the radio waves is
Answer:
Explanation: as,
v=f∧
v=200×10³×1.5×10³
v=2.7×10^7ms⁻¹
The velocity of the radio waves is 3 × 10⁸ ms⁻¹.
A radio station frequency = 200 KH
wavelength = 1.5 km
How the velocity of the radio waves are calculated?Radio waves in the electromagnetic spectrum has the longest wavelength and it will always be below 300GHz. The radio waves can be generated with acceleration through some charged particles. Only through the transmitter via antenna the radio waves can gets transmitted. Radio waves can be used in all the electronic devices as mobile phones, radio communication, radars and navigations.
V = f λ
Velocity, v = ( 200 × 10³ ) × ( 1.5 × 10³ )
= ( 300 × 10⁶ )
v = 3 × 10⁸ ms⁻¹.
Hence, the velocity of the radio waves is 3 × 10⁸ ms⁻¹.
Learn more about the radio waves,
https://brainly.com/question/21995826
#SPJ2
A motorcycle moving with velocity and 30m/s accelerate with 4m/s2 to gain velocity of 6mls. calculate its time to gain that velocity
Using first equation of kinematics
[tex]\boxed{\sf v=u+at}[/tex]
[tex]\\ \sf\longmapsto t=\dfrac{v-u}{a}[/tex]
[tex]\\ \sf\longmapsto t=\dfrac{30-6}{4}[/tex]
[tex]\\ \sf\longmapsto t=\dfrac{24}{4}[/tex]
[tex]\\ \sf\longmapsto t=6s[/tex]
A rocket travels vertically at a speed of 1200 km/h. The rocket is tracked through a telescope by an observer located 16km from the launching pad. Find the rate at which the angle between the telescope and the ground is increasing 3 min after lift-off. Round your answer to the nearest hundredth rad/hr
Answer:
w = 0.01 t⁻² rad/h
Explanation:
Let's use trigonometry to find the elevation angle of the telescope, we assume that the rocket remains fixed in the telescope.
tan θ = CO / CA
the adjacent leg is CA = 16 km = 16 10³ m
Let's use kinematics to find the height of the rocket
v = y / t
y = v t
this height is equal to the opposite leg
CO = v t
we substitute
tan θ = vt / 16
tan θ = 1200/16 t
tan θ = 75 t
θ = tan⁻¹ ( 75 t )
speed is defined by
w = dθ/dt
w = [tex]\frac{1}{1 + (75 t)^2} \ 75[/tex]
as time increases we can neglect the 1 of the denominator
w = 1/75 t²
w = 0.0133 t⁻²
Using three significant figures
w = 0.01 t⁻² rad/h
for this answer the time must be given in hours
A van of mass 1200kg is moving with speed of 90km/hr. It is brought in 3 seconds by applying brakes. Calculate the force applied to bring van to rest.
Answer:
Explanation:
The main equation to solve this is F = ma, where F is the force applied to the brakes with respect to its acceleration. We have the mass that we need, but we do not have the acceleration. That's the first thing we have to find. However, our velocity needs to be stated in m/s and right now it's in km/h. Converting that:
[tex]90\frac{km}{hr}*\frac{1000m}{1km}*\frac{1hr}{3600s} =25\frac{m}{s}[/tex] Now we're ready to find the acceleration:
[tex]a=\frac{v_f-v_0}{t}[/tex] where the top line there translates to the final velocity minus the initial velocity.
[tex]a=\frac{0-25}{3.0}[/tex] so the acceleration is -8.3 m/s/s
We can use that now in the force equation above:
F = 1200(-8.3) and
F = -1.0 × 10⁴ N (that's 10,000 N to the correct number of sig dig's; the negative sign means that the force is being applied in the direction opposite to that which the van is currently moving)
They want a mixture of 150 grams of water at 60 degrees Celsius, using hot water at 90 degrees Celsius and cold water at 14 degrees Celsius, how many grams of water should be used per face?
Answer:
Explanation:
Here,
Final mass(m)=150g
Final Temperature(t)=60°C
Temperature of hot water(t1)=90C
Temperature of cold water(t2)=14C
Let the grams of water to be used per face be m1 grams and (150-m1) grams for hot and cold water respectively.
We know that,
Heat lost by hot body=Heat gained by cold body
or, m1 s1 Δt1=m2 s2 Δt2
or, m1 (t1-t)=(150-m1) (t-t2) [∵s1=s2, SHC of water is taken to be same]
or, m1 (90-60)=(150-m1) (60-14)
or, 30m1=6900-46m1
or, 76m1=6900
∴m1=90.79g
(150-m1)=59.21g
Hence, 90.79g and 59.21 g hot and cold water must be used respectively.
how do atoms lose electrons ?
Answer:
Explanation:
By being close to an atom that will gladly take the electrons being offered.
Suppose you are talking about Be. It is in the second column. It has two outer electrons that can be given away. It will not give away one of the two remaining electrons because they are too close to the + nucleus.
Along comes a Fluorine atom. It has 7 electrons in its outer ring. The chemistry of the situation allows it to take on one of the two electrons Be is offering. It is all a matter of charges and attractions.
Another Fluorine atom will take on the remaining electron from the Be. The outer ring cannot take on more than 1 electron, but that is enough
