Write true if the statement is correct and false if the statement
1. Magnetic poles always appear in pair.
2. Iron and nickel are examples of magnetic materials.
3. The two ends of a magnet are called magnetic poles.
4. Two similar magnetic poles attract each other
5. If one end of an iron bar attracts one pole of a com
Grade 7 Physics
then the iron bar must be a magnet.
Match the terms in column A with the phrases in colu
B​

A gun recoils back when the bullet is fired due to conservation of momentum. Conservation of momentum suggest that - the net change of momentum in a closed system must be zero.

Therefore in equation form -

[tex]mv - mu = 0[/tex]

Why does a gun recoil when a bullet is fired?

When a bullet is fired, the gun exerts a force on the bullet through the trigger (this is action) in a particular direction. According to Newton's Third Law, we know to every action there is an equal and opposite reaction; action and reaction act on different bodies. So, the bullet will also exert an equal and opposite reaction on the gun in the opposite direction. That is why a gun recoils when a bullet is fired from it.

Answer:

The unit rate is $0.22 lb

Explanation:

The given parameters are;

The price for 18 lb = $3.99

We have;

The unit rate is the price for one unit. Whereby the unit of measurement is the lb, we have that one unit = 1 lb.

Therefore, given that 1 lb = 18 lb/18, the price of 1 lb which is the unit rate is given as follows;

18 lb price = $3.99

Divide both sides by 18 to get;

18 lb/18 =  $3.99/18 = $0.221[tex]\bar 6[/tex]

Therefore, we have;

1 lb = 18 lb/18 = $0.221[tex]\bar 6[/tex]

The unit rate, which is the cost for 1 lb to the nearest hundredth = $0.22/lb.

Let B = a i + b j + c k. Then the cross product of A = i + 2j - k with B is

A × B = ( i + 2j - k ) × ( a i + b j + c k )

A × B  = a ( i × i ) + 2a ( j × i ) - a ( k × i )

… … … + b ( i × j ) + 2b ( j × j ) - b ( k × j )

… … … + c ( i × k ) + 2c ( j × k ) - c ( k × k )

A × B = 0 - 2a k - a j

… … … + b k + 0 + b i

… … … - c j + 2c i - 0

A × B = (b + 2c) i + (-a - c) j + (b - 2a) k

So we have

3 i - j + 5 k = (b + 2c) i + (c - a) j + (b - 2a) k

which gives us the system of equations,

{ b + 2c = 3

{ -a - c = -1

{ -2a + b = 5

Solve for a, b, and c.

• Eliminate c from the first two equations:

(b + 2c) + 2 (-a - c) = 3 + 2 (-1)

-2a + b = 1

But -2a + b = 5, and 5 ≠ 1, so there is no such vector B that satisfies the cross product!

Answer:

at the top of the tree I hope it will help you please follow me

Answer:

The final velocity of the car is 36 m/s.

Explanation:

Given;

initial velocity of the car, u = 20 m/s

time of the car acceleration, t = 4 s

acceleration of the car, a = 4 m/s²

the final velocity of the car is calculated as;

v = u + at

where;

v is the final velocity of the car

v = 20 + (4 x 4)

v = 36 m/s

Therefore, the final velocity of the car is 36 m/s.

Explanation:

We know that kWh is a commercial unit of energy.

Also, 1 Joule = 1 watt × 1 seconds

[tex]1\ kWh=1kW \times 1\ h[/tex]

Since ,1 h = 3600 s and 1kW = 1000 W

[tex]1\ kWh=1000\ W \times 3600\ s\\\\1\ kWh = 36\times 10^5\ W-s\\\\1\ kWh=36\times 10^5\ J[/tex]

So, the relation is : [tex]1\ kWh=36\times 10^5\ J[/tex]

1 watt is defined as the power of an appliance when the energy is transferred at a rate of 1 Joule per second.

Answer:  c or b

Explanation:

Answer:

1)substance A will require 910 J of heat to increase the temperature by 10°C.

2) Substance B

3) Substance A

Explanation:

1) The meaning of the statement: "specific heat capacity of A is 910 J/kg °C" is that 1 kg of substance A will require 910 J of heat to increase the temperature by 10°C.

2) While heating equal mass of all the three substances supplied with equal amount of heat, Substance B will gain more temperature due to the fact that substances of lesser specific heat capacity always tend to gain or loose heat within a short period of time.

3) While keeping equal mass at the three substances heated for the same temperature of 100°C and kept on a wax slab, substance A will go down more in depth due to the fact that heat is preserved for a longer period of time for substances that have higher specific heat capacity.

Answer:

13.1

Explanation:

that's what I'm gonna go with, but u can research more

Answer:

I think its A

Explanation:

A lysosome is a membrane-bound cell organelle that contains digestive enzymes. Lysosomes are involved with various cell processes. They break down excess or worn-out cell parts. They may be used to destroy invading viruses and bacteria.

The function of lysosomes is to remove waste as well as destroying a cell after it has died, called autolysis. A lysosome is an organelle containing digestive enzymes which it uses to function as the digestion and waste removal for cells, food particles, bacteria, etc.

Answer:

22236 mi

Explanation:

Answer:

P is momentum.

Explanation:

Brainliest Please!!?!!

- ElizabethKate.

Answer:

length=2

Explanation:

You simply find the zeros of the quartic polynomial

The factored form is (x+1)(x-5)(x-2)=0

The zeros become -1,5 and 2

Dimension 5 is already given and the question says length>width and 2>-1

Therefore length=2

Answer:

n =1.33 revolutions

Explanation:

Uniform Circular Motion

The angular speed can be calculated in two different ways:

[tex]\displaystyle \omega=\frac{v}{r}[/tex]

Where:

v = tangential speed

r = radius of the circle described by the rotating object

Also:

[tex]\omega=2\pi f[/tex]

Where:

f = frequency

Solving for f:

[tex]\displaystyle f=\frac{\omega}{2\pi}[/tex]

Since the frequency is calculated when the number of revolutions n and the time t are known:

[tex]\displaystyle f=\frac{n}{t}[/tex]

We can solve for n:

n=f.t

The particle moves in a circle of r=90 m with a speed v=25 m/s. Thus the angular speed is:

[tex]\displaystyle \omega=\frac{25}{90}[/tex]

[tex]\displaystyle \omega=0.278\ rad/s[/tex]

Now we calculate f:

[tex]\displaystyle f=\frac{0.278}{2\pi}[/tex]

[tex]f=0.04421\ Hz[/tex]

Calculating the number of revolutions:

n = 0.04421*30

n =1.33 revolutions

Explanation:

Most waves appear complex because they result from two or more simple waves that combine as they come together at the same place at the same time—a phenomenon called superposition. Waves superimpose by adding their disturbances; each disturbance corresponds to a force, and all the forces add

introurself please

There would be two forces acting on the box parallel to the floor, with a net force of

∑ F = p - f = m a

where p = magnitude of the push, f = mag. of friction, m = mass of the box, and a = acceleration. To find p, we first need f .

There are also only two forces acting on the box perpendicular to the floor, with net force

∑ F = n - w = 0

where n = mag. of normal force of the floor on the box and w = weight of the box. The net force is 0 because the box is only accelerating parallel to the floor.

w = m g, where g = 9.8 m/s² is the mag. of the acceleration due to gravity, so we can solve for n :

n = w = m g

n = (22 kg) (9.8 m/s²)

n = 215.6 N

The kinetic friction is proportional to the normal force by a factor of the given coefficient of friction, µ = 0.17, such that

f = µ n

f = 0.17 (215.6 N)

f = 36.652 N

Now solve for the required pushing force:

p - 36.652 N = (22 kg) (1.9 m/s²)

p ≈ 78 N

Answer:

0

Explanation:

Answer:

The answer is True.

Answer:

4

Explanation:

I added all of them and them minus the 5.

Answer:

The value is  [tex]T = 1702.91 \ N[/tex]  

Explanation:

From the question we are told that

   The mass of the laser sensor is  [tex]m = 137 \ kg[/tex]

    The horizontal acceleration of the helicopter and the sensor is  [tex]a = 2.63 \ m/s^2[/tex]

Generally the net force on the cable is              

[tex]F = T - W = ma[/tex]

    Here W  is the weight of the sensor  which is evaluated as [tex]W = m * g = 137 * 9.8 = 1342.6 \ N[/tex]

     So

     [tex]T - 1342.6 = 137 * 2.63[/tex]

=>   [tex]T = 360.31 + 1342.6[/tex]  

=>   [tex]T = 1702.91 \ N[/tex]  

Answer:

If lone pairs of electrons, electrons not bonded to other atoms, are located in the molecule, this will change the molecular geometry, not the electron geometry. If all the electron groups are bonded, with no lone pairs, then the electron geometry and molecular geometry are the same.

Answer:

Thermal energy is the total kinetic energy of moving particles of matter, and the transfer of thermal energy is called heat. Thermal energy from the bonfire is transferred to the hands by thermal radiation. ... This is how the fire warms the hands of someone sitting near the bonfire.May

Answer:

Thermal Radiation

Explanation:

Type of heat transfer Hope this helped <3

Answer:

light bulb

Explanation:

Answer:

its B

Explanation:

the movement of charged particles in a conductor

Charged particles move through a conductor best describes an Electric current.

A stream of charged particles, such as electrons or ions, traveling through an electrical conductor or a vacuum is known as an electric current.

Charge carriers, which can be any of a number of particle kinds depending on the conductor, are the moving particles. Electrons flowing over a wire are frequently used as charge carriers in electric circuits.

They can be electrons or holes in semiconductors. Ions are the charge carriers in an electrolyte, whereas ions and electrons are the charge carriers in plasma, an ionized gas.

Therefore, Charged particles move through a conductor best describes an Electric current.

To learn more about electric current, refer to the link:

https://brainly.com/question/2264542

#SPJ2

Answer:

This question is incomplete

Explanation:

This question is incomplete because of the absence of the figure. However, wavelength can be described as the distance between two crests (identical points) of a wave (as illustrated in the picture attached). Thus, a wave with a large/great wavelength must have a long distance between the two crests and has nothing to do with the number of crests/wavelengths since distance between crests could also be small.

Hence, what appears to be the correct option is the last option (Wavelength shown with 1 wavelength stretched over a long distance).

Answer:

Its B.

Explanation:

Im took the exam.

The answer Is kilometers