Answer: - 7500N
Explanation:
Given the following :
Initial Velocity of car = 108km/hr
Time taken to stop after applying brakes = 4s
Mass of passengers in car = 1000kg
Force exerted by the brakes on the car =?
After 4s, then final Velocity (V) = 0
Initial Velocity (u) of the car = 108km/hr
108km/hr = (108 × 1000)m ÷ (3600)s = 30m/s
Force exerted = mass(m) × acceleration(a)
Acceleration of car = Change in Velocity with time
a = (v - u) / t
a = (0 - 30) / 4
a = - 30/ 4
a = - 7.5m/s^2
Therefore,
Force exerted = mass(m) × acceleration(a)
Force exerted = 1000kg × (-7.5)m/s^2
Force exerted = - 7500N
Answer:
The force exerted by the brakes on the motor car is -7500 N.
Explanation:
Given :-
Mass of the motor car along with passengers (m)= 1000 kgInitial velocity (u) = 108 km/hTime taken (t) = 4 sTo find :-
The force exerted by the brakes on the motor car.Solution :-
Since the car stops, the final velocity (v) will be 0 m/s.
• Initial velocity (u) = 108 km/h.
Converting initial velocity into m/s.
We know that,[tex] \sf{1\:km/h=\dfrac{5}{18}\:m/s}[/tex]
Then initial velocity,
= [108 × 5/18 ] m/s
= 30 m/s
Now find the force exerted by the brakes.
★ Formula used :
[tex]{\boxed{\sf{F=\dfrac{m(v-u)}{t}}}}[/tex]
[put values][tex]:\implies \sf \: F= \dfrac{1000(0 - 30)}{ 4} \\ \\ : \implies \sf \: F \: = \dfrac{ - 30000}{4} \\ \\ : \implies \sf \: F \: = - 7500[/tex]
The force exerted by the brakes on the motor car = -7500 N.
•The negative sign of force(F) means that the force was applied in opposite direction of motion.
__________________An object with more mass has more kinetic energy than an object with less
mass, if both objects are moving
OA) at the same speed
OB) in the same direction
OC) in opposite directions
Explanation:
The kinetic energy of an object is given in terms of its mass and object as :
[tex]K=\dfrac{1}{2}mv^2[/tex]
An object with more mass has more kinetic energy. An object with less mass, if both objects are moving at the same speed, in opposite directions, will have less kinetic energy. The square of v will give positive number.
An object rotates describing a horizontal circumference when subjected to a centripetal force F. What centripetal force will act on the object if the radius of the circle is doubled and the kinetic energy of the object is halved? A) F/4 B) F/2 C) F D) 4F please explain this to me : (
Answer:
Option A: F/4
Explanation:
Centripetal force, [tex]F = \frac{mv^{2} }{r}[/tex]
Where v = speed
r = radius
Since Kinetic Energy, [tex]E_{k} = 0.5 mv^{2}[/tex]
Writing centripetal force in terms of kinetic energy, [tex]F = \frac{2 E_k}{r}[/tex]
If the initial radius of the circle, r₁ =r
The doubled radius, r₂ = 2r
If the initial kinetic energy, [tex]KE_1 = E_{k}[/tex]
The halved kinetic energy, [tex]KE_2 = 0.5E_{k}[/tex]
Therefore, the new Centripetal force becomes:
[tex]F_{2} = \frac{2(0.5 E_k)}{2r} \\F_{2} = \frac{0.5 E_k}{r}\\F_{2} =\frac{1}{4} * \frac{2 E_k}{r}\\Since, F = \frac{2 E_k}{r} \\F_{2} =\frac{1}{4} * F\\F_{2} =\frac{F}{4}[/tex]
4. ____________ occurs when one object slides over another.
a. Sliding friction
b. Static friction
c. Rolling friction
d. Net force
Answer:
A. Sliding friction
Explanation:
Sliding friction is weaker than static friction
Answer:
Rolling Friction
Explanation:
I know this because the definition of rolling friction is : type of friction that happens when one body rolls over another
Which objects would sink in honey, which has a density of 1.4 g/cm³? Check all that apply.
Answer:
any object that has density more than 1.4
Explanation:
The object that has density more than 1.4 is denser than the honey
An astronaut is moving in space when a big explosion occurs about 50 meters behind him. How will the astronaut come to know about the explosion?
Choose:--
From the sound of the explosion
From the light due to the explosion
From light and sound due to the explosion
From the vibrations due to the explosion
Answer:
The correct answer is B.
The astronaut will know due to the light from the explosion.
Explanation:
Sound and vibrations require a medium such as air to travel through. Space, there is no air. Only a vacuum. So sound and vibrations are unable to travel. Light requires no medium to travel. It can go through a vacuum.
Therefore the Astronaut will see a bright flash of light as it travels from the explosion to outer space. It is also important to note that light can travel very far because nothing else interacts with its wave particles and as such, it cannot be impeded.
Cheers!
A student with a mass of 66.0 kg climbs a staircase in 44.0 s. If the distance between the base and the top of the staircase is 14.0 m, how much power will the student deliver by climbing the stairs
[tex]power = 205.8 \: watt \\ solution \\ mass = 66 \: kg \\ time = 44 \: sec \\ distance = 14 \\ now \\ power = \frac{w}{t} \\ \: \: \: \: \: \: \: \: = \frac{f \times d}{t} \\ \: \: \: \: \: = \frac{m \times g \times d}{t} \\ \: \: \: \: \: \: = \frac{66 \times 9.8 \times 14}{44} \\ \: \: \: \: = \frac{9055.2}{44} \\ \: \: \: \: \: = 205.8 \: watt \\ hope \: it \: helps[/tex]
what is brightness. help asap
Answer:
The subjective visual sensation related to the intensity of light emanating from a surface or from a point source.
Calculate the transfer of energy by a force of 15N when it moves the object by a distance of 5m
a. In the direction of the force
b. In a direction at 60° to the direction of the force
c. At right angles to the force
NEED EXPLAINATION
Answer:
a) 75 J
b) 37.5 J
c) 0
Explanation:
Work is the force exerted on an object causing it to move, Work is the product of force and displacement. Work is not done if the force and displacement are at right angles to each other. It is given by:
[tex]Work(energy)=Fxcos(\theta)[/tex]
F is the force, x is the displacement and Θ is the angle between force and displacement.
a) Force (F) = 15N and distance (x) = 5. Since it is in the direction of the force, Θ = 0
[tex]Work(energy)=Fxcos(\theta)= 15*5*cos(0)=75J[/tex]
b) Force (F) = 15N and distance (x) = 5. Θ = 60
[tex]Work(energy)=Fxcos(\theta)= 15*5*cos(60)=37.5J[/tex]
c) Force (F) = 15N and distance (x) = 5. Θ = 90
[tex]Work(energy)=Fxcos(\theta)= 15*5*cos(90)=0[/tex]
A rubber band that has been stretched has gained ____ energy
OA) heat
OB) kinetic
OC) potential
D) chemical
Answer: potential
Explanation:
A sheet of paper 3.0 cm by 4.0 cm is lying on the desk. If the atmospheric pressure is 1.013105 Pa, what is the total force exerted on the top side of the paper by the atmosphere?
Answer:
132.56N
Explanation:
Pressure is defined as force per unit area.
Expressed mathematically as;
P = F/A
Where P-pressure
F-force
A-area
From the above formula,
F= P×A
= 1.1013 × 10^5 × (3×4/10000)
= 11.013×12 =132.56N
Note: the unit of measure in cm is converted to m and since 100cm makes 1m for each sides 3cm and 4cm we convert to 'm' by dividing by 100 twice giving division by 10000)
The unit of measure Pa means Pascal and is the same as N/m2
Write down any four points that should be considered during household wiring
Answer:
USE RUBBER CLOVES
USE A PLIER
USE CONDUCTIVE WIRES
SWITHC OFF THE MAIN SWITCH WHILE WIRRING
Explanation:
Is a 5kg ball is rolling to the right and has a velocity of 4 m/s what is the momentum of the ball
Answer:
∆p = 20 kg * m/s
Explanation:
The change in momentum is the mass of the body multiplied by the change in its velocity.
In formula form ∆p = m * ( ∆v ).
with m = 5 kg and ∆v = 4 m/s
∆p = 5 kg * 4 m/s
∆p = 20 kg * m/s
What is the most likely reason why these early flowers gradually changed to many different types of flowers over time?
Answer:
The flowers adapted to environmental conditions.
Explanation:
The object will feel minimum force of gravity at the
Answer:
space , small amount of gravity is found in the space ,infact we can say that there is no gravity in the space
Answer:
Poles
Explanation:
The gravitational force is maximum at the equator and minimum at the poles.
a 50.0kg bicyclist on a 10.0kg bicycle speeds up from a 5.00m/s to 10.0m/s
Answer:
The total kinetic energy before accelerating = 750 JThe total kinetic energy after accelerating = 3,000 JTotal work done = 2,250 JExplanation:
Given:
Mass of bicyclist = 50 kg
Mass of bicycle = 10 kg
Initial velocity (u) = 5 m/s
Final velocity (v) = 10 m/s
Find:
(a) What was the total kinetic energy before accelerating = ?
(b) What was the total kinetic energy after accelerating = ?
(c) How much work was done to increase the kinetic energy of the bicyclist = ?
Computation:
Total mass (M) = 50 kg + 10 kg = 60 kg
1. The total kinetic energy before accelerating = 1/2[Mu²]
The total kinetic energy before accelerating = 0.5[(60)(5)²]
The total kinetic energy before accelerating = 750 J
2. The total kinetic energy after accelerating = 1/2[Mv²]
The total kinetic energy after accelerating = 0.5[(60)(10)²]
The total kinetic energy after accelerating = 3,000 J
3. Total work done = Δ K.E
Total work done = 3,000 J - 750 J
Total work done = 2,250 J
Salt is dissolved in a flask of tap water . Distilling the mixture causes the salt to separate from the water. Which type of energy is required to begin the distilling process
A train is moving west with an initial velocity of 20m/s accelerates at 4m/s for 10 seconds during this time the train moves a distance
Answer:
400m
Explanation:
From Newton's law of motion;
S = ut + 1/2 at2
Where U is initial velocity
a is acceleration
t is velocity hence;
S is distance covered
S = 20×10 + 1/2 × 4×(10)^2
= 200 + 200 = 400m
A water distiller which is used to purify water. The distiller boils water and then condenses most of the water vapour back to water. (a) The water distiller is filled with 5.0 kg of water at 20 °C The specific heat capacity of water = 4 200 J/Kg °C Calculate the energy needed to raise the temperature of the water to 100 °C ___________________________________________________________________
Answer:
Energy needed 1680kJExplanation:
The quantity of heat required to raise the temperature of water to 100 degrees is expressed as
[tex]Q= mc(T2-T1)[/tex]
Given data
mass of water = 5kg
initial temperature T1= 20 °C
final temperature T2= 100 °C
Specific heat capacity of water= 4 200 J/Kg °C
[tex]Q= 5* 4 200(100-20)\\Q= 21000(80)\\Q= 1680000\\Q= 1680kJ[/tex]
A 2kg object is dropped from a height 10m.Calculate the speed of the object after it has fallen 5m, assuming there is no resistance. g= 10 N/kg
Answer:
10m/s
Explanation:
[tex]d=v_ot+\dfrac{1}{2}at^2[/tex]
Since there is no initial velocity as the object is dropped, you can write the following equation:
[tex]5=\dfrac{1}{2}(10)t^2 \\\\1=t^2 \\\\t=1[/tex]
Now that you know how long the fall took, you can use another physics equation to find the velocity at that point.
[tex]v_f=v_o+at[/tex]
Since there once again is no initial velocity, you can rewrite this as:
[tex]v_f=at=(10)(1)=10m/s[/tex]
Hope this helps!
The kinetic energy the object has at any point during the fall is exactly the potential energy it lost by falling to that height.
Potential energy = (mass) · (gravity) · (height)
Change of potential energy = (mass) · (gravity) · (change of height)
Change of potential energy = (2 kg) · (10 m/s ) · (-5 m)
Change of potential energy = 100 Joules
Kinetic energy = (1/2) · (mass) · (speed²)
Kinetic energy = (1 kg) · (speed² )
100 J = (1 kg) · (speed²)
Speed² = (100 J) / (1 kg)
Speed² = (100 kg-m²/s²) / (1 kg)
Speed² = (100 m²/s²)
Speed = 10 m/s
Which force does not operate at a distance of 1 m?
A. Weak nuclear
O B. Electric
C. Gravitational
D. Magnetic
Answer:
A
Explanation:
A wire having resistance 20 ohm is bent to make a closed square.What is the resistance across the diagonal of square?
Answer:
5 Ω
Explanation:
When it is bent into a square, each side of the square will get 5 Ω resistance. As considered diagonally ,path of the wire between to diagonal points is the two sides of the square (that is half the length of the wire connected in parallel position). Which gives 10 ohm parallel to 10 ohm wire. So it finally read as 5 Ω wire
why is no one helping?
Answer:
First one is hyperopia, second is myopia
Explanation:
Hyperopia is when the image is formed behind the retina.
Myopia is when images are formed infront of the retina.
Concrete and steel expand to almost the same amount when they are heated. Explain why you think this is lucky?
Answer:
While making a bridge or a building, the first thing that comes to our mind is that these are always made by the combination of concrete and steel. Concrete is cheap, but it has the property of breaking when it is twisted or under tension. Steel is expensive, If we made the whole thing with it, it will cost a lot. To provide strength under a reasonable cost, we use the combination of concrete and steel. Another postive point which they have together is that they both expand equally under heat, because they have the same coefficient of thermal expansion. It proves really useful, because if they had different coefficients of thermal expansions, one would expand more than the other, which will create tensions in the mixture and would break it easily. In the case, many cracks would start to appear in the bridge or buildings, which will eventually break them.
The power of a machine is 6000 W. This machine is scheduled for design improvements. Engineers have reduced the
time for the output by one half from 15 s to 7.5 s. What work would be required to cut the time in half.
Step #1
Step #2
Step #3
Explanation:
Work = power × time
W = (6000 W) (7.5 s)
W = 45,000 J
A 2 kg billiard green ball is moving toward the 2 kg white billiard ball on a pool table. The green ball is moving with an initial speed of 4 m/s and the white ball is at rest. The two balls collide and move apart. The white ball moves away from the green ball with a speed of -6 m/s. With what speed does the green ball move away?
Answer:
10m/s
Explanation:
collisions results in objects sticking together or not sticking together after collision and so they do move with a common velocity or uncommon velocity respectively.
Parameters from the question:
Mass of green billiard balls, m1=2kg
Mass of white billiard balls, m2=2kg
Initial velocity for green billiard balls ,u1=4m/s
Initial velocity for white billiard balls ,u2 = 0m/s( since the body is at rest meaning it wasn't moving)
Final velocity of green billiard ball after collision is,v1= unknown
Final velocity of white green billiard ball after collision is, V2 = -6m/s.
Now from Newton's third law of motion that action and reaction must be equal and opposite;hence change in momentum before collision would be the same after collision since energy is conserved.
Hence,
m1U1 + m2U2 = m1V1 +m2V2
2×4 + 2×0 = 2×V1 + 2× (-6)
8 = 2V1 -12
8+12=2V1
20=2V1
10=V1
V1=10m/s
explain the causes of yaa asantewaa war of 1900
Answer: the conflict began when a british representative - Sr. Frederick Mitchell Hodgson sat on the golden stool.
Explanation:
since the stool wasn't a throne, when Yaa Asantewaa found out, he led a rebellion which killed 1000 British and allied African soldiers and 2,000 Ashanti.
good luck with your assignment :)
When the kinetic energy of particles in a substance decreases, what also decreases?
93
The size of the particles in the substance.
The number of particles in the substance.
The substance's specific heat.
The substance's temperature.
Answer: D
The substance's temperature
Explanation:
According to kinetic theory, increase in temperature causes increase in kinetic energy of particles in a system.
When the kinetic energy of particles in a substance decreases, it has nothing to do with the size of the particles and the specific heat capacity of the particles or substance. But it a clear indication that the substance temperature has also decreased.
Answer:
D
Explanation:
What is the name of the change in state by which some more energetic molecules in a liquid leave the surface, leaving the rest of the liquid slightly cooler.
Answer:
evaporation
Explanation:
vapor is having higher temperature (also energy) that the liquid it left behind.
that's why the water vapor leave the surface of water which can only have a maximum temperature as 100°C
A) Is it possible for an object that, object with zero acceleration have velocity? If yes give an example if not give its proof.
Answer:
Yes, in case of uniform velocity
Explanation:
This is the case of uniform velocity. If a body covers equal displacement in equal intervals of time, then the velocity of a body is said to be ‘Uniform Velocity’. It meas that the velocity of a body remains constant during the motion and it does not change.
Since, acceleration is defined as the rate of change of velocity.
Therefore, if there is no change in velocity or in other words the change in velocity is zero, then the acceleration is also zero.
a = ΔV/t = 0/t
a = 0 m/s²
So, the acceleration of the body is 0 m/s², but it has a uniform velocity
Hence, it is possible for an object that, object with zero acceleration have velocity, which is the case case of uniform velocity.
what is the wavelength of radio waves transmitted by an FM station at 90MHz where 1M=10^6, and speed of radiowave is 3*10^8m/s
Answer:
λ = 3.33 m
Explanation:
Given:
Frequency = f = 9 × 10⁷ Hz
Speed = v = 3 × 10⁸ m/s
Required:
Wavelength = λ = ?
Formula:
v = fλ
Solution:
Putting the givens in the formula
v = fλ
λ = [tex]\frac{v}{f}[/tex]
λ = [tex]\frac{3*10^8}{9*10^7}[/tex]
λ = 0.33 × 10¹
λ = 3.33 m
