PLEASE HELP!

A 2457 kg car moves with initial speed of 18 ms-?. It is stopped in 62 m by its brakes.
How much work is done by the brakes?

A Torque is a twisting force, or turning moment, it is a vector quantity with both magnitude and direction e.g Turning the handle of a cork-screw clockwise and then counterclockwise will advance the screw first inward and then outward By convention, counterclockwise torques are positive and clockwise torques are negative.

The direction is perpendicular to both the radius from the axis and to the force. It is conventional to choose it in the right hand rule direction along the axis of rotation.

Counterclockwise is the positive rotation direction and clockwise is the negative direction.

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Answer:

A) 58 km

B) 30 mins

Explanation:

In pic details

graph in pic

Answer:  You need to use Newton's law for the equation --->

Explanation: G  ×  M  ×  m / separation. Thats how youll get your answer !!

Explanation:

The initial kinetic energy [tex]KE_0[/tex] is

[tex]KE_0 = \frac{1}{2}mv_0^2 = \frac{1}{2}(400\:\text{kg})(10\:\text{m/s})^2[/tex]

[tex]\:\:\:\:\:\;\:= 2×10^4\:\text{J} = 20\:\text{kJ}[/tex]

The final kinetic energy [tex]KE[/tex] is

[tex]KE = \frac{1}{2}mv^2 = \frac{1}{2}(400\:\text{kg})(30\:\text{m/s})^2[/tex]

[tex]\:\:\:\:\:\:\:= 1.8×10^5\:\text{J} = 180\:\text{kJ}[/tex]

The work done W on the car is

[tex]W = \Delta{KE} = KE - KE_0[/tex]

[tex]\:\:\:\:\:\:\:= 180\:\text{kJ} - 20\:\text{kJ} = 1.6×10^5\:\text{J}[/tex]

The power expended P is

[tex]P = \dfrac{W}{t} = \dfrac{1.6×10^5\:\text{J}}{15\:\text{s}} = 10667\:\text{Watts}[/tex]

[tex]\:\:\:\:\:= 10.7\:\text{kW}[/tex]

Answer:

The distance traveled before takeoff is 1720 m

Explanation:

a = + 3.2 m/s²

t = 32.8 s

Vᵢ = 0 m/s

d = ?

Now,

d = Vᵢ × t + 0.5 × a × t²

d = (0 m/s) × (32.8 s) + 0.5 × (3.20 m/s²) × (32.8 s)²

d = 1720 m

Thus, The distance traveled before takeoff is 1720 m

-TheUnknownScientist 72

Answer:

Explanation:

Conservation of momentum

Let's say the first child was headed north

North momentum

75(0) + 20(2) + 15(3sin45) = (75 + 20 + 15)vn

vn = 0.6529 m/s

East momentum

75(0) + 20(0) + 15(3cos45) = (75 + 20 + 15)ve

ve = 0.28927 m/s

θ = arctan(0.28927/0.6529)

θ = 23.896...

θ = 24° east of north

Hi there!

We can use the equation:

d = v₀t + 1/2at²

Where:

v₀ = initial velocity downward

a = acceleration due to gravity

t = time

Plug in given values:

d = 4(12) + 1/2(9.8)(12²)

d = 48 + 705.6 = 753.6 m

Addition of a proton to germanium  will convert it to arsenic (element 33) having different properties.

The atomic number of an atom is the number of protons in the nucleus of the atom. The atomic number serves as the identity of an atom. If the atomic number is changed by adding or removing protons, the identity of that atom changes.

Hence, when a proton is added to germanium, the  atom would become arsenic (element 33) and have different properties.

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Answer: Its B and D

I had the same question on usatestprep

Explanation:

Since the neutron is only moving at 1000 m/s, we are going to ignore the relativistic effects on its mass and energy. The mass of a neutron in [tex]m_n = 1.67×10^{-27}\:\text{kg}[/tex] so its kinetic energy KE is

[tex]KE = \frac{1}{2}m_nv^2[/tex]

[tex]\:\:\:\:\:\:\:\:= \frac{1}{2}(1.67×10^{-27}\:\text{kg})(10^3\:\text{m/s})^2[/tex]

[tex]\:\:\:\:\:\:\:\:= 8.35×10^{-22}\:\text{J}[/tex]

A photon's energy E is defined as

[tex]E = h\nu[/tex]

where [tex]\nu[/tex] is the photon's frequency and h is the Planck's constant. Solving for the frequency, we get

[tex]\nu = \dfrac{E}{h} = \dfrac{8.35×10^{-22}\:\text{J}}{6.63×10^{-34}\:\text{J-s}}[/tex]

[tex]\:\:\:\:\: = 1.26×10^{12}\:\text{Hz}[/tex]

which is right around the infrared radiation range.

Answer:

not sure i need points

Explanation:

11.4 m/s

Explanation:

The cord will break when the centripetal force exerted on it meets or exceeds the maximum tension [tex]T_{max}[/tex] that it can handle.

[tex]T_{max} = m\dfrac{v_{max}^2}{r}[/tex]

Solving for [tex]v_{max},[/tex] we get

[tex]v_{max}^2 = \dfrac{rT_{max}}{m}[/tex]

or

[tex]v_{max} = \sqrt{\dfrac{rT_{max}}{m}} =\sqrt{\dfrac{(1.3\:\text{m})(60\:\text{N})}{(0.6\:\text{kg})}}[/tex]

[tex]\:\:\:\:\:= 11.4\:\text{m/s}[/tex]

Answer: 20

Explanation:

Explanation:

The orbiting period of a satellite at a height h from earth' surface is

T=2πr32gR2

where r=R+h.

Then, T=2π(R+h)R(R+hg)−−−−−−−−√

Here, R=6400km,h=1600km=R/4

T=2πR+R4−−−−−−√R(R+R4g)−−−−−−−−−⎷=2π(1.25)32Rg−−√

Putting the given values,

T=2×3.14×(6.4×106m9.8ms−2)−−−−−−−−−−−−√(1.25)32=7092s=1.97h

Now, a satellite will appear stationary in the sky over a point on the earth's equator if its period of revolution around the earthh is equal to the period of revolution of the earth up around its own axis whichh is 24h. Let us find the height h of such a satellite above the earth's suface in terms of the earth,'s radius.

Let it be nR.Then

T=2π(R+nR)R(R+nRg)−−−−−−−−−−√

=2π(Rg)−−−−−√(1+n)32

=2×3.14(6.4×106m/s9.8m/s2)−−−−−−−−−−−−−−−⎷(1+n)32

(5075s)(1+n)32=(1.41h)(1+n)32

For T=24h, we have (24h)=(1.41h)(1+n)32

or (1+n)32=241.41=17

or 1+n(17)23=6.61

or n=5.61

The height of the geostationary satellite above the earth's surface is nR=5.61×6400km=6.59×104km.

Answer:it’s C

Explanation:

by using graph of velocity vs. time for two objects, Item 4 and Item 5 statement makes an accurate comparison of the motions for objects. thus option C is correct.

velocity is the  rate of change of the position of the object with respect to  reference and it is complicated but velocity is basically speeding a particular object in a specific direction.

Velocity is a vector quantity which means both magnitude (speed) and direction are combinedly define define velocity. The SI unit of velocity is meter per second (ms-1) and the magnitude or the direction of velocity of a body changes leads to acceleration.

Speed and velocity are the two closest term but the major difference between speed and velocity is that speed gives us an idea that the object with the faster rate of movement r where as  velocity  speed up as well as  tells us the direction of the body

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Explanation:

In this chapter, we will study the important concepts of kinetic energy and the

closely related concept of work and power.

A- Kinetic Energy

Kinetic energy is a physical quantity, which is associated with the moving objects

and defined as:

K = ½ mv2

If the body is stationary (v=0), its kinetic energy is zero. The SI unit of kinetic

energy is kg.m2

/s2

or Joule (J), where 1 J=1 kg.m2

/s2

. Kinetic energy is a scalar

quantity.

B- Work

The work is defined as the ability to perform a force along a certain displacement.

There are different types of work as follows:

1- Work done by a constant force

The work done by the constant force F is given by the scalar product of the force F

and the displacement d.

WF = F.d = Fd cosθ

where θ is the angle between the force and displacement. The above equation means

that the work is the product of the displacement magnitude by component of the

force parallel to the displacement. Therefore, work is a scalar quantity (only

magnitude, no direction) and can be positive, negative, or zero. The SI unit of work

is (N.m) or joule (J) where 1 N.m = 1 J.

Special cases and remarks:

• If the angle between the force and displacement is zero (parallel), the work is

WF = F d (maximum work)

Answer:

negatively charged particle

valence electron  is a electron of an atom, located in the outermost shell (valence shell ) of the atom, that can be transferred to or shared with another atom.

Answer:

Explanation:

Normal force of the surface on the box will be

N = mg - Fsinθ

Ν = 10(9.8) - 600sin37

N = -263

As normal force cannot be less than zero, the applied force lifts the crate off the surface.

Now it's just a matter of finding the acceleration

In the horizontal direction, the acceleration is

a = F/m

a = (600cos37) / 10

a =  47.9181... m/s²

the crate weight is mg = 10(9.8) = 98 N.

In the vertical direction the acceleration is

a = ((600sin37 - 98) / 10)

a = 26.3089... m/s²

total acceleration is

a = √(47.9181² + 26.3089²)

a = 54.6653... m/s²

s = ½at²

t = √(2s/a)

t = √(2(1.0)/54.6653)

t = 0.19127...

t = 0.19 s

Hi there!

We know that:

U (Gravitational Potential Energy) = mgh

Where:

g = acceleration due to gravity (m/s²)

m = mass (kg)

h = height/displacement (m)

Plug in the values:

U = 3 × 9.8 × 14 = 412 J

Answer:

D

Explanation:

Process of elimnination + it's the only one that makes sense

An object will begin moving from rest when acted upon by forces that are greater in one direction than in any other direction. Hence, Option (D) is correct.

The definition of force in physics is: The push or pull on a massed object changes its velocity. An external force is an agent that has the power to alter the resting or moving condition of a body. It has a direction and a magnitude.

When  forces that are greater in one direction than in any other direction, resultant will be  unbalanced forces.  Unbalanced forces are those acting on a body when the net force acting on the body is greater than zero. The body alters its state of motion when unbalanced forces act on it.

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The force of friction needed to overcome to move the box is 29.4N

According to Newton's second law;

[tex]\sum F_x = ma_x\\[/tex]

Taking the sum of force along the plane;

[tex]F_m -F_f = ma\\F_m -F_f = 0\\F_m=F_f = \mu R[/tex]

This shows that the moving force is equal to the frictional force

Given that

[tex]\mu = 0.6\\R = mg = 49N[/tex]

Get the frictional force;

Since

[tex]F_f = \mu R\\F_f = 0.6 \times 49\\F_f = 29.4N[/tex]

Hence the force of friction needed to overcome to move the box is 29.4N

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Answer:

15[m].

Explanation:

1) the required distance is AD, for more info see the attached picture.

2) [tex]AD=\sqrt{AA_1^2+A_1D^2} =\sqrt{81+144}=15[m].[/tex]

Answer:

M1 + M2 = 0   total momentum before explosion = momentum after explosion where M1 is the lighter fragment

M1 V1 + 7 M1 V2 = 0

V2 = -V1 / 7      

The lighter fragment will slide 7 times as far - 39.2 mm because it must have 7 times as much velocity - assuming the distance slid is proportional to the original velocity

The modern atomic model is called the nuclear atomic model.

Therefore the correct answer is option C.

There are many types of atomic models proposed in past based on their individual assumptions and the experimentations

John Dalton's atomic model.

The Plum Pudding Model, developed by J.J. Thomson,

Rutherford's model provided an explanation for the presence of a nucleus inside the atom.

In accordance with the current atomic model, atoms have a nucleus made up of protons and neutrons and an ethereal gradient or cloud surrounding them that houses electrons;

The modern atomic model is called the nuclear atomic model.

Thus, the correct answer is option C.

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Answer:

Cement, iron, and steel all work great!

Answer:

Explanation:

s 0.12 + 1.20(1.80) = 2.28 m from the top.

Answer:

0.067 births per chipmunk per year

Explanation:

I took the test