A car is coasting backwards downhill at a speed of 3.0 m/s when
the driver gets the engine started. After 2.5 sec, the car is
moving
uphill at 4.5 m/s. Assuming that uphill is the positive
direction, what is the car's average acceleration?

Answer:For a perfectly elastic collision, the final velocities of the carts will each be 1/2 the velocity of the initial velocity of the moving cart. For a perfectly inelastic collision, the final velocity of the cart system will be 1/2 the initial velocity of the moving cart.

Explanation:

Answer:

irrational

Explanation:

Answer:

B

Explanation:

The two most abundant elements in a main sequence star are the hydrogen and helium. Thus, the correct option is B.

The main sequence is a continuous and distinctive band of the stars which appears on the plots of stellar color versus the brightness. These color-magnitude plots are known as the Hertzsprung–Russell diagrams, named after their co-developers, Ejnar Hertzsprung and Henry Norris Russell. The stars on this band are known as the main-sequence stars or the dwarf stars. These are the most numerous true stars present in the universe and include the Sun.

Hydrogen is the most abundant element which is possessed by the main sequence star. After hydrogen atom, the most abundant element which is found is helium. This gets accumulated in the star's core through the process of nuclear fusion.

Therefore, the correct option is B.

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When a car sounds its horn as it approaches and moves away from an observer, there is a change in pitch known as a Doppler shift. During the approach, the received frequency is higher than the emitted frequency. ]Thus, option B is correct.

You hear a fairly high-pitched sound, like an ambulance coming at you with sirens blazing. This is because the moving ambulance is squishing the sound waves in front of the car together.

A good illustration of the Doppler effect is this. Since the effective wavelength is reduced due to an approaching source moving closer throughout the sound wave's period while the wave's velocity remains constant, the pitch is increased. Similar to this, a sound source that is fading away will have a lower pitch.

Therefore, Sound waves are pushed closer together, increasing wavelength and decreasing frequency.

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Answer:B

Explanation:

Explanation:

In a balanced equation, the total number of atoms of each element on the reactant side is equal total number of atoms on the product side

Answer:

a moving object will keep moving if not stopped

the sun being at the center of the solar system

Explanation:

Galileo is known for being the first person make a telescope, there fore being the first person to see that the sun is in the center of the solar system. he also came up with the theory that if something is pushed, it would keep moving until stopped by another force. For example, say you drop your pencil, it keeps falling until it hits the ground. That is exactly what Galileo did in his  Leaning Tower of Pisa experiment and found that theory to be true.

Galileo’s discoveries were later used in Newton’s laws include the following

below:

Galileo was a scientist which invented the telescope and used it to view the

center position of the Sun in the solar system.

He also proposed  that if something is pushed, it would keep moving until

stopped by another opposing force. His discoveries were found to be true

and were later used in  Newton’s laws.

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Answer:

The normal force experienced by the car is approximately 8223.2 N

Explanation:

The question relates to banking of road where the centripetal force for the circular motion of the vehicle is provided by the horizontal component of the normal reaction

The mass of the vehicle that moves around the curve, m = 900 kg

The incline of the curve, θ = 20°

The speed with which the vehicle moves around the curve, v = 12.5 m/s

The radius of the curve, R = 50 meters

We have;

[tex]N \cdot sin(\theta) = \dfrac{m \cdot v^2}{R}[/tex]

Where;

θ = The angle of inclination of the road = 20°

N = The normal force experienced by the car

m = The mass of the car = 900 kg

v = The velocity with which the car is moving = 12.5 m/s

R = The radius of the curve around which the vehicle moves = 50 m

[tex]\therefore N = \dfrac{m \cdot v^2}{R \cdot sin(\theta)} = \dfrac{900 \times (12.5)^2}{50 \times sin(20^{\circ})} = 8223.1998754586828969046217875927[/tex]

The normal force experienced by the car = N ≈ 8223.2 N.

Answer:

You will do twice the work of climbing 1 stair.

Explanation:

To obtain the answer to the question, we shall determine the work done on each case. This is illustrated below:

Case 1 ( climbing 2 stairs):

Mass (m) = m

One stair = 4 m

Height (h) = 2 × 4 = 8 m

Acceleration due to gravity (g) = 10 m/s²

Workdone 1 (Wd₁) =?

Wd₁ = mgh

Wd₁ = m × 10 × 8

Wd₁ = 80 × m

Case 2 (Climbing 1 stair)

Mass (m) = m

Height (h) = 4 m

Acceleration due to gravity (g) = 10 m/s²

Workdone 2 (Wd₂) =?

Wd₂ = mgh

Wd₂ = m × 10 × 4

Wd₂ = 40 × m

Now comparing the Workdone in both case:

Workdone 1 (Wd₁) = 80 × m

Workdone 2 (Wd₂) = 40 × m

Wd₁ / Wd₂ = 80 × m / 40 × m

Wd₁ / Wd₂ = 2

Cross multiply

Wd₁ = 2 × Wd₂

Thus, we can see that the Workdone in climbing 2 stairs is twice the Workdone in climbing 1 stair.

Therefore, you will do twice the work of climbing 1 stair.

Answer:

90.07794 grams

Explanation:

Answer:

[tex]P_J=195N[/tex]

Explanation:

From the question we are told that

[tex]Mass\ of T-joe\ M_J=65\\Velocity\ of T-joe\ V_J=3m/s\\Mass of\ T-Brud\ M_B=50kg\\Velocity\ of T-Brud\ V_B=3m/s\\[/tex]

Generally the equation for momentum is mathematically given by

[tex]P=mv[/tex]

Therefore

T-Joe momentum [tex]P_J[/tex]

[tex]P_J=65*3[/tex]

[tex]P_J=195N[/tex]

Answer:

The property of the wave marked X is related to the source of the wave

Explanation:

The source of of origin of waves

Electromagnetic wave are waves that consists of varying electric and magnetic field that vibrate perpendicular to each other and to the direction of propagation of the wave and they are therefore transverse waves and transfer energy

Electromagnetic waves originate from the vibration of charged particles that gives off varying electric and magnetic fields

Mechanical waves are defined as waves that require a material medium such as air, water, metal, plastic, stretched leather, or wood to propagate

Mechanical waves originate from vibration of the particles of a medium

Sound waves which is a form of longitudinal mechanical waves that propagates by the vibration of the particles of a given medium about a point parallel to the direction of propagation of the wave.

Answer:

Both are attractive as well as repulsive.

Explanation:

(Like poles repel, like charges repel; unlike poles attract, unlike charges attract).

There are two types of charges that form electric fields: positive and negative charges. Magnetic fields are formed by charges and are related with two magnetic poles, north and south (but moving charges).

The attraction and repulsion of electric charges produce both electric and magnetic fields.

The force released by magnets when they attract or repel each other is known as magnetism. An electric force is the attracting or repulsive interaction between any two charged things.

Similarities are as follows:

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Answer:

5600N

Explanation:

Given parameters:

Mass of car  = 700kg

Initial velocity  = 10m/s

Final velocity  = 30m/s

Displacement  = 50m

Unknown:

Net force acting on the car  = ?

Solution:

To find the force acting on a body, it is pertinent we know the mass and acceleration.

 Force  = mass x acceleration

Now;

 Let us find the acceleration from the kinematics equations:

 v²  = u²  + 2aS

 v is the final velocity

 u is the initial velocity

 a is the acceleration

 S is the distance

  30²  = 10²  + (2 x a x 50)

 900 = 100 + 100a

      100a  = 800

           a  = 8m/s²

Therefore;

     Force  = 700 x 8  = 5600N

Answer:

v = 381 m/s

Explanation:

Linear Speed

The linear speed of the bullet is calculated by the formula:

[tex]\displaystyle v=\frac{x}{t}[/tex]

Where:

x = Distance traveled

t = Time needed to travel x

We are given the distance the bullet travels x=61 cm = 0.61 m. We need to determine the time the bullet took to make the holes between the two disks.

The formula for the angular speed of a rotating object is:

[tex]\displaystyle \omega=\frac{\theta}{t}[/tex]

Where θ is the angular displacement and t is the time. Solving for t:

[tex]\displaystyle t=\frac{\theta}{\omega}[/tex]

The angular displacement is θ=14°. Converting to radians:

[tex]\theta=14*\pi/180=0.2443\ rad[/tex]

The angular speed is w=1436 rev/min. Converting to rad/s:

[tex]\omega = 1436*2\pi/60=150.3776\ rad/s[/tex]

Thus the time is:

[tex]\displaystyle t=\frac{0.2443\ rad}{150.3776\ rad/s}[/tex]

t = 0.0016 s

Thus the speed of the bullet is:

[tex]\displaystyle v=\frac{0.61}{0.0016}[/tex]

v = 381 m/s

Answer:

e

Explanation:

It will take 74.07 minutes, for a transformer to transfer 2.3 X 10^6 J of energy from a 120-V circuit to a 345-V circuit with a current of 1.5 A

The rate of doing work is known as power. The Si unit of power is the watt.

Power =work/time

The mathematical expression for the power is as follows

P = VI

where P is the power

V is the voltage

I is current passing through the circuit

For a transformer to transfer 2.3 X 10^6 J of energy from a 120-V circuit to a 345-V circuit with a current of 1.5 A

Power on the delivery side of the transformer by using the above formula

P = VI

P= 345 V × 1.5 A

P= 517.5 watt

Power = electrical energy /time

517.5 watt = 2.3 X 10^6 J / time

time = 4444.44 seconds

       =74.07 minutes

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Answer:

The description of the energy of the skier at point W is,

At point W, potential energy is greatest and kinetic energy is least

Explanation:

The given parameters are;

The highest point of the skier's path = Point W

The lowest point of the skier's path = Point X

The height of the peak after point X = Intermediate between point W and point X

The potential energy of the skier, P.E. = m·g·h

The kinetic energy of the skier, K.E. = 1/2·m·v²

The total mechanical energy of the skier, M.E. = P.E. + K.E.= Constant

Where;

m = The mass of the skier

g = The acceleration due to gravity = 9.8 m/s²

h = The height of the skier

v = The velocity of the skier

Therefore, the P.E. of the skier is highest at the highest point of the skier's path which is the point W, where h = Maximum

Similarly, the potential energy of the skier will be lowest at point X which is the lowest point on the skier's path

From P.E. + K.E. = constant, the kinetic energy will be least at point W, where the potential energy is highest.

Therefore, the description of the energy of the skier at point W is that the potential energy is greatest and kinetic energy is least.

Answer:

MKS stands for Meter, Kilogram and second. In this system of unit mass is given in Kilogram, length in meter and time in second. ... CGS system stands for Centimeter- Gram- Second system. In CGS system, length is measured in centimeters mass is measured in grams and time is in seconds.

Answer:

[tex] \underline{ \boxed{F_m = 3.35 { \times 10}^{ - 2} N}}[/tex]

Explanation:

[tex]since \: in \: this \: case \to \: \underline{ v }\: is \perp \: to \:\underline{ q} \\ then \: the \: magnetic \: force \: (F_m) \: is \: max = qvB \sin(90) \\ F_m = qvB \times (1) = qvB \\ hence \to \\ F_m = qvB \\ where \\ \: q = 0.75 C : v = 235m {s}^{ - 1} : B = 1.9 { \times 10}^{ - 4} T \\ therefore \to \\ F_m = 0.75 \times 235 \times 1.9 { \times 10}^{ - 4} \\ F_m = 176.25 \times 1.9 { \times 10}^{ - 4} \\ F_m = 0.0334875 = 3.35 { \times 10}^{ - 2} N \\ \boxed{F_m = 3.35 { \times 10}^{ - 2} N}[/tex]

Answer:7.5j

Explanation:

P=w/s

Answer:

m = 3.57

Explanation:

Given that,

Sergei uses a lever to lift a heavy rock. He obtains a 2.5m lever and places the fulcrum 0.7m from the rock.

We need to find the ideal mechanical advantage of Sergei's lever.

It is equal to the ratio of resistance arm to the effort arm. In terms of length it is given by :

[tex]m=\dfrac{d_2}{d_1}\\\\m=\dfrac{2.5}{0.7}\\\\=3.57[/tex]

So, the ideal mechanical advantage of the lever is 3.57.

Answer:

Voltage, Zero

Explanation:

If an electric circuit has 0 A of current running through it, then the ✔ voltage must be ✔ zero.

Answer:

Voltage, zero

Explanation:

Answer:

Answer a)  Force on A equal to force on B

Answer a) The electric field points to the left in the location A

Explanation:

12)

Recall that the magnitude of the electrostatic force is given by:

[tex]F=k\frac{q*Q}{d^2}[/tex]

therefore in magnitude it is the same for charge q than for charge Q.

(Answer a for the first problem - 12)

13)

Recall that the electric filed points outwards for a positive charge, therefore at the location of charge q, the field must be pointing towards the left.

Answer:

1kg/ L

Explanation:

Answer:

Amoeba, paramecium, euglena are the examples of unicellular organism

Explanation:

Hope you like my answer

Answer:

Cp = 397 [J/kg*K]

Explanation:

By means of the energy equation for heat transfer in substances and objects, we can calculate the specific heat. In this way, we have the following equation.

[tex]Q=m*C_{p}*DT[/tex]

where:

Dt = temperature change = 10 [K]

m = mass = 0.5 [kg]

Q = heat = 1985 [J]

Cp = specific heat [J/kg*K]

Now replacing:

[tex]1985=0.5*C_{p}*10\\C_{p}=\frac{1985}{0.5*10}\\C_{p}=397[\frac{J}{kg*K} ][/tex]

Answer:

K = 960 J

Explanation:

Given that,

Mass of a child = 20 kg

Mass of a sled = 10 kg

Speed of child on sled = 8 m/s

We need to find the kinetic energy of the sled with the child.

The total mass of child and the sled = 20 kg + 10 kg

= 30 kg

The formula for the kinetic energy of an object is given by :

[tex]K=\dfrac{1}{2}mv^2\\\\K=\dfrac{1}{2}\times 30\times (8)^2\\\\K=960\ J[/tex]

Hence, the kinetic energy of the sled with the child is 960 J.

Answer:

Explanation:

They require a medium.

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Answer:

- They require a medium

Explanation:

Sound waves are, by definition, waves of vibrating matter. You need a medium like a solid, liquid or gas to transmit sound waves. A vacuum is space without matter, and so sound cannot be transmitted through it. Outer space is, for the most part, a vacuum, so that line from Alien rings pretty true:

"In space, no one can hear you scream."

There would be more hurricanes because hurricanes from by water.

More rain because you would get more precipitation.

Higher flooding if a storm comes through.