What must be the reaction force when someone hits a tree with an axe?

Answer:

Explanation:

Velocity is related to Displacement.

Average velocity = Displacement / Time difference

Answer:

The height reached by the ball=0.459 m

Explanation:

We are given that

[tex]\theta=30^{\circ}[/tex]

Initial speed, u=6 m/s

We have to find the maximum height reached by ball.

Maximum height reached by ball

[tex]h=\frac{u^2sin^2\theta}{2g}[/tex]

Where [tex]g=9.8m/s^2[/tex]

Substitute the values

[tex]h=\frac{6^2sin^230^{\circ}}{2\times 9.8}[/tex]

[tex]h=\frac{36\times \frac{1}{4}}{2\times 9.8}[/tex]

[tex]h=0.459 m[/tex]

Hence, the height reached by the ball=0.459 m

Answer:

Option (c) is correct.

Explanation:

The apparent change in the frequency of light due to the relative motion between the source and the observer is called Doppler's effect.

When the source is moving towards the observer which is at rest, the apparent frequency increases and if the observer is moving away the frequency of sound decreases.

It occurs for both light and sound.  

So, to explain the blue shift of light in the universe is due to the Doppler's effect of light.

Answer:

It is proved.

Explanation:

PV = n R T

where,  P is the pressure, V is the volume, n is the number of moles, R is the gas constant, T is  the absolute temperature.

Unit of pressure is Pascal= Newton/square meter = [tex][ML^{-1}T^{-2}][/tex]

Unit of volume is cubic meter = [tex][L^{3}][/tex]

So, the unit of P V

[tex][ML^{-1}T^{-2}] \times [L^{3}]\\\\[ML^2T^{-2}}[/tex]

[tex][ML^{2}T^{-2}][/tex]

It is same as the unit of energy.

hence proved.  

Answer:

This question is incomplete but the completed question is below

As a girl pushes an object across a wood floor, she suddenly comes to an area where the floor has been waxed recently, making it slippery. What becomes true of the coefficient of kinetic friction? A. The coefficient of kinetic friction increases. B. The coefficient of kinetic friction decreases. C. The coefficient of kinetic friction becomes zero. D. The coefficient of kinetic friction becomes negative.

The correct option is B

Explanation:

Coefficient of kinetic friction can be defined as the frictional force resisted by the motion of an object. From the question, it might take the girl to apply a force equivalent to just half that of the weight of the object to overcome friction to keep the object moving on a wood floor. Once she gets to the waxed area, the frictional force reduces, thereby also reducing the coefficient of kinetic friction further. Thus, she will be able to use less than half of the force (equivalent to less than half of the weight of the object) to push the object.

Thus, the correct option is B.

Answer:

True

Explanation:

Formula for speed is;

Speed = distance/time

Now, if an object covers an equal distance in equal time intervals, it means the speed will remain the same.

For example if an object covers 3 m every 1 second it means speed will always be; 3/1 = 3 m/s.

Thus the statement is correct.

Mendeleev wrote down atomic mass

Answer:

A. Buoyancy.

hope it helps

Answer:

The answer is "physics ".

Explanation:

Physics is the branch of science that addresses the properties of crystalline and its interaction with the fundamental elements of the universe. It covers subjects ranging in quantum mechanics with extremely little ones with quantum mechanics to the whole cosmos. You must be constant whether you like it or not, thus everyone must learn physics, irrespective of whether they're in Uganda, and plenty of other countries should have physics to dare study.

Answer:

The definition of acceleration is a change in the rate of motion, speed or action.

Acceleration is the rate of change of velocity.

[tex]acceleration = \frac{(final \: velocity - initial \: velocity)}{time} \\ or \\ a = \frac{(v - u)}{t} \\ \\ The \: S.I. \: unit \: of \: acceleration \: is \: \frac{m}{ {s}^{2} } \: or \: m {s}^{ - 2} [/tex].

My last year's notes on acceleration is attached. Hope it helps you!!

Answer:

The specific heat of air is 100  J/kg°C.

Explanation:

mass, m = 5 kg

Temperature change, T' - T =  37 °C - 22 °C = 15°C

heat, H = 7500 J

let the specific heat of air is c.  

The formula of heat is

H = m c (T' - T)

7500 = 5 x c x 15

c = 100 J/kg°C

Answer:

Option D. 5Ω e 0.6 A

Explanation:

1. Determination of the equivalent resistance.

We'll begin by calculating the equivalent resistance of resistor B and resistor C. This can be obtained as follow:

Resistor B (R₆) = 2 Ω

Resistor C (R꜀) = 2 Ω

Equivalent Resistance (R₆꜀) =?

R₆꜀ = R₆ × R꜀ / R₆ + R꜀ (parallel connection)

R₆꜀ = 2 × 2 / 2 + 2

R₆꜀ = 4 / 4

R₆꜀ = 1 Ω

Finally, we shall determine the equivalent resistance of the circuit. This can be obtained as follow:

Resistor A (Rₐ) = 2 Ω

Equivalent resistance of resistor B and C (R₆꜀) = 1 Ω

Resistor D (Rₔ) = 2 Ω

Equivalent Resistance (R) =?

R = Rₐ + R₆꜀ + Rₔ (series connection)

R = 2 + 1 + 2

R = 5 Ω

Thus, the equivalent resistance of the circuit is 5 Ω

2. Determination of the total current in the circuit.

Potential difference (V) = 3 V

Equivalent resistance (R) = 5 Ω

Total current (I) =?

V = IR

3 = I × 5

Divide both side by 5

I = 3 / 5

I = 0.6 A

Thus, the total current in the circuit is 0.6 A

Summary:

Equivalent resistance = 5 Ω

Current = 0.6 A

Option D gives the current answer to the question.

Answer:

30m/ s

Explanation:

this is an example of a projectile, where the path traced by the ball will be a downward parabola.

one must know that the vertical velocity of an object having projectile motion is zero at the top of its trajectory and that the horizontal velocity remains constant throughout.

this means, at the top of the trajectory the ball's overall speed will be equal to its horizontal velocity.

and horizontal velocity is given 30 m/s

hence, overall speed of the ball = 30m/ s

Answer:56

Explanation: I did the test

Answer:

It collects sound waves and channels them into the ear canal (external auditory meatus), where the sound is amplified. The sound waves then travel toward a flexible, oval membrane at the end of the ear canal called the eardrum, or tympanic membrane. Sound waves cause the eardrum to vibrate.

It collects sound waves and channels them into the ear canal (external auditory meatus), where the sound is amplified. The sound waves then travel toward a flexible, oval membrane at the end of the ear canal called the eardrum, or tympanic membrane. Sound waves cause the eardrum to vibrate.                                                                                                               Explanation:

The Outer Ear

The auricle (pinna) is the visible portion of the outer ear. It collects sound waves and channels them into the ear canal (external auditory meatus), where the sound is amplified.

The sound waves then travel toward a flexible, oval membrane at the end of the ear canal called the eardrum, or tympanic membrane. Sound waves cause the eardrum to vibrate.

The Middle Ear

The vibrations from the eardrum set the ossicles into motion. The ossicles are actually tiny bones — the smallest in the human body. The three bones are named after their shapes: the malleus (hammer), incus (anvil) and stapes (stirrup). The ossicles further amplify the sound.

The tiny stapes bone attaches to the oval window that connects the middle ear to the inner ear. The Eustachian tube, which opens into the middle ear, is responsible for equalizing the pressure between the air outside the ear and that within the middle ear.

The Inner Ear

The sound waves enter the inner ear and then into the cochlea, a snail-shaped organ. The cochlea is filled with a fluid that moves in response to the vibrations from the oval window. As the fluid moves, 25,000 nerve endings are set into motion. These nerve endings transform the vibrations into electrical impulses that then travel along the eighth cranial nerve (auditory nerve) to the brain.

The brain then interprets these signals, and this is how we hear.

The inner ear also contains the vestibular organ that is responsible for balance.

Answer:

The main reason is to avoid explosion

Explanation:

When we carry out distillation process, it will get to a point where gases/steam are released due to evaporation, if we do not create a channel for exit they will build up in the apparatus and will ultimately lead to explosion

Question

Using atomic weight, crystal structure, and atomic radius data tabulated inside the front cover of thebook, compute the theoretical densities of aluminum (Al), nickel (Ni), magnesium (Mg), and tungsten (W), and thencompare these values with the measured densities listed in this same table. The c/a ratio for magnesium is 1.624.

Explanation:

Answer:

9.78 m/s^2

Explanation:

Acceleration due to gravity at equator is 9.78m/s^2

Answer:

Explanation:

This is a centripetal force problem where tension supplies the centripetal force needed to keep the stone moving in a circular manner. That formula for that is

[tex]F_c=T=\frac{mv^2}{r}[/tex] and filling in what we know:

[tex]1*10^{-4}=\frac{.02v^2}{1}[/tex] and solve that for v:

[tex]v=\sqrt{\frac{1*10^{-4}}{.02} }[/tex] which gives us a velocity of .07 m/s. Anything greater than this will break the string.

Hi there!

[tex]\large\boxed{D. \text{ } 3.0 kg}}[/tex]

Use the following equation to solve:

F = ma, where:

F = Force (N)

m = mass (kg)

a = acceleration (m/s²)

Thus:

15 = 5m

15/5 = m

mass = 3 kg

Answer:

U = - ∫ F dx

U = - 3F₀

Explanation:

Force and potential energy are related

         F = [tex]- \frac{dU}{dx}[/tex]

         dU = - F dx

        ∫ dU = - ∫ F dx

        U- U₀ = - ∫ F dx

to solve the problem we must know the form of the force, if we assume that F = F₀ and U₀ = 0 for x = 0

         U = - F₀ 3

On a hot dry day, the amount of water vapour present in atmosphere is less. Thus, water present inside the desert cooler evaporates more, thereby cooling the surroundings more. Hence, a desert cooler cools better on a hot dry day.

Answer:

The type of image formed on a screen by a convex lens is real, enlarged and inverted.

Explanation:

A lens can be defined as a transparent optical instrument that refracts rays of light to produce a real image.

Basically, there are two (2) main types of lens and these includes;

I. Diverging (concave) lens.

II. Converging (convex) lens.

A converging lens refers to a type of lens that typically causes parallel rays of light with respect to its principal axis to come to a focus (converge) and form a real image.

Basically, the type of image formed on a screen by a converging (convex) lens is real, enlarged and inverted because it is usually thick across the middle (causing rays of light to converge) but thin at the lower and upper edges.

Answer:

Explanation:

As the ball rises, its PE increases because the potential energy is equal to the mass of the ball times gravity times the height of the ball. The higher the height, the higher the PE.

Answer:

According to the law of conservation of energy its kinetic energy is getting converted in to potential energy because of gain in height. So, if the velocity of a ball goes on decreasing when it is thrown vertically upwards. When its velocity becomes zero, its potential energy becomes maximum.

Answer:

[tex]a=0.33\ m/s^2[/tex]

Explanation:

For washer 2,

v₁ = 0.13 m/s

v₂ = 0.36 m/s

t₁ = 1.92

t₂ = 2.61

We need to find the acceleration of waster 2.

[tex]a=\dfrac{v_2-v_1}{t_2-t_1}\\\\a=\dfrac{0.36-0.13}{2.61-1.92}\\\\a=\dfrac{0.23}{0.69}\\\\a=0.33\ m/s^2[/tex]

So, the acceleration of washer 2 is [tex]0.33\ m/s^2[/tex].

Answer:

.33

Explanation:

Answer:

[tex]N_B-W_B = 0[/tex]

Explanation:

There are two forces acting on object B. If we consider the law of equilibrium, then the two forces must be equal in magnitude, for the object to remain in equilibrium position:

[tex]N_B = W_B\\\\N_B-W_B = 0[/tex]

Therefore, the correct answer of the given question, from the given choices, is:

[tex]N_B-W_B = 0[/tex]

Answer:

It was proposed by Isaac Newton

Explanation:

The law of universal attraction of expression

          F = [tex]G \ \frac{m_1m_2}{ r^2}[/tex]G m1m2 / r ^ 2

where G is a constant, m₁ and m₂ are the masses of the bodies and r the distance between them.

It was proposed by Isaac Newton

With this law Newton explained that the force that pulls the moon towards the earth is the same as that which attracts an apple towards the earth

Answer:

(n) alluvial fan sandbar

Explanation:

Answer:

The energy dissipated is 27600 J.

Explanation:

Voltage, V = 230 V

Current, I = 4 A

time, t = 30 s

The energy is given by

E = V I t

E = 230 x 4 x 30

E = 27600 J