Exercise 25
1. Ablock of wood is 10 cm long, by 4 cm broad
by 15 cm thick. The block weighs 31 g.
Find the density of the wood in kg/m!​

Answer:

Kyra is more precise.

Explanation:

Kyra is more precise as she has included the exact point second it had dissolved whereas Pari just rounded it  to the closest number making her write a whole number that was rounded down.

Answer: Fg < Fq

Explanation: just took the lab test edge 2020

The electromagnetic force is greater than the gravitational force option third Fg < Fq is correct.

It is a force imposed by one charge on another as a result of the field. The electrostatic force produced by one line charge on another line charge separated by r is determined by the charge potency of each charge as well as the separation distance between them.

Force of gravity is given by:

[tex]\rm F_g=\dfrac{Gm_1m_2}{r^2}[/tex]

The electrostatic force is given by:

[tex]\rm F_q = \dfrac{kq_1q_2}{r^2}[/tex]

On the atomic scale, electrons, for example, have very little mass but a very large charge. As a result, electromagnetic forces rule.

Thus, the electromagnetic force is greater than the gravitational force option third Fg < Fq is correct.

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Answer:

hello your question is incomplete below is the complete question

A 2.0 kg block starts from rest on a positive x axis 3.0m from the origin and thereafter has an acceleration given by a= 4.0i - 3.0jin m/s2. At the end of 2.0 s, its angular momentum about the origin is ______.

answer : L = ( 2 kg ) [(-18m^2/s)k]

Explanation:

velocity vector(v)  = (4.0i - 3.0j )(2.0s)

position vector(r) = ( 3.0m)i

determine the angular momentum about the origin

L = m ( r * v )

attached below is the detailed solution

Answer:

Explanation:

Given the acceleration,

[tex]v(t) = 4ti - 3tj[/tex]

So,

[tex]v(2) = 8i - 6j[/tex]

similarly,

[tex]x(t) = (3 + 2t^2) i - 1.5t^2 j[/tex]

so,

[tex]x(2) = 11i - 6j[/tex]

Angular momentum,

[tex]=mx(2)*v(2)\\\\=2*((-6x0-0x-6)i +(0x8-11x0)j +(11x-6--6x8)k)\\\\=2*(0i +0j -18k)\\\\=(-36kg.rad/s)k[/tex]

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Answer:

Explanation:

Given:

Specific heat of gold  = 0.031cal/°C

Specific heat of silver  = 0.057cal/°C

To know the metals that will heat up faster, we must understand the meaning of specific heat capacity.

It is the amount of heat required to raise the temperature of 1g of a substance by 1°C.

Now,

The higher the specific heat capacity the more energy it is required to heat up the substance.

So, Gold with a specific heat capacity of 0.031cal/°C  will heat up faster.

Answer:21

Explanation:every body said

Answer:

gravitational potential energy and kinetic energy

Explanation:

Answer:

Explanation:

From the question we are told that

   The mass of the tennis ball is  [tex]m = 0.060 \ kg[/tex]

    The speed is  [tex]u = 15 \ m/s[/tex]

    The initial height of the ball is  [tex]h_o = 2.2 \ m[/tex]

     The height considered is  [tex]h = 9.5 \ m[/tex]

Generally the time taken to reach the considered height is mathematically evaluated from the equation of motion as follows

           [tex]h = h_o + ut - \frac{1}{2} gt^2[/tex]

=>         [tex]9.5 = 2.2 + 15t - \frac{1}{2} * 9.8 t^2[/tex]

=>         [tex]7.3 = 15t - 4.9t^2[/tex]

=>          [tex]4.9t^2 -15t + 7.3[/tex]

solving the above equation using quadratic formula

           [tex]t= 0.6070 \ s[/tex] and  [tex]t_1 = 2.454 \ s[/tex]

Generally from kinematic equation we have that

        [tex]v = u - gt[/tex]

=>     [tex]v= 15 - 9.8 * 0.6070[/tex]

=>      [tex]v= 9.0514 \ m/s[/tex]

Note if we had used the second values of time the velocity at 9.5 \ m would have been negative which is not correct given that at maximum height velocity is zero

Answer:

answer is in photo

Answer:

Steam distillation is a separation process which consists in distilling water together with other volatile and non-volatile components.

Answer: no it shouldn't be

Explanation:

Answer:

D H2 + O2 ---> H2O

Explanation:

Answer:

I am not sure what the answer is but keep reading.

Explanation:

The answer is not D or A for sure

Answer: Job and career

Explanation:

Work is associated with job and career. If somebody is having a great career and if somebody wants a great career he will look for a job that is fitting his career and in that way, he will work for it to have an even better career which will bring him a better job.

Answer:

The velocity of the two cars is 10 m/s after the collision.

Explanation:

Law Of Conservation Of Linear Momentum

The total momentum of a system of bodies is conserved unless an external force is applied to it. The formula for the momentum of a body with mass m and velocity v is

P=m.v

If we have a system of bodies, then the total momentum is the sum of them all

[tex]P=m_1v_1+m_2v_2+...+m_nv_n[/tex]

If some collision occurs, the velocities change to v' and the final momentum is:

[tex]P'=m_1v'_1+m_2v'_2+...+m_nv'_n[/tex]

In a system of two masses, the law of conservation of linear momentum  takes the form:

[tex]m_1v_1+m_2v_2=m_1v'_1+m_2v'_2[/tex]

If both masses stick together after the collision at a common speed v', then:

[tex]m_1v_1+m_2v_2=(m_1+m_2)v'[/tex]

The car of mass m1=1000 Kg travels at v1=25 m/s and collides with another car of m2=1500 Kg which is at rest (v2=0).

Knowing both cars stick and move together after the collision, their velocity is found solving for v':

[tex]\displaystyle v'=\frac{m_1v_1+m_2v_2}{m_1+m_2}[/tex]

[tex]\displaystyle v'=\frac{1000*25+1500*0}{1000+1500}[/tex]

[tex]\displaystyle v'=\frac{25000}{2500}[/tex]

v' = 10 m/s

The velocity of the two cars is 10 m/s after the collision.

Please find attached photograph for your answer.

Answer:

This question appear incomplete

Explanation:

This question appear incomplete because there is no list of closest correct answer there. Although can still be well attempted.

The formula to be used here is

average speed = distance ÷ time

The unit of speed here would be meters per second (m/s). However, some of the lines do not really fall on a measurable line on the graph and can only be "best assumed".

A: distance is 1600 meters

time appear to be 4 seconds (definitely less than 5 seconds according to the graph).

speed = 1600 ÷ 4

speed = 400 m/s

B: distance is 1600 meters

time appear to be 18 seconds (definitely less than 20 seconds according to the graph)

speed = 1600 ÷ 18

speed = 88.89 m/s

C: distance is 1600 meters

time is 65 seconds

speed = 1600 ÷ 65

speed = 24.62 m/s

D:  distance is 1600 meters

time is 105 seconds

speed = 1600 ÷ 105

speed = 15.24 m/s

E: distance is 1100 meters

time is 120 seconds

speed = 1100 ÷ 120

speed = 9.17 m/s

F: distance is 500 meters

time is 120 seconds

speed = 500 ÷ 120

speed = 4.17 m/s

G: distance appear to be 250 meters

time is 120 seconds

speed = 250 ÷ 120

speed = 2.08 m/s

H: distance appear to be 50 meters

time is 120 seconds

speed = 50 ÷ 120

speed = 0.42 m/s

The average speed for each object are:

1. The average speed of A is 400 m/s

2. The average speed of B is 88.89 m/s

3. The average speed of C is 24.62 m/s

4. The average speed of D is 15.24 m/s

5. The average speed of E is 9.17 m/s

6. The average speed of F is 4.17 m/s

7. The average speed of G is 2.08 m/s

8. The average speed of H is 0.33 m/s

Average speed is defined as the total distance travelled divided by the total time taken to cover the distance.

With the above formula, we can obtain the average speed for each object as follow:

1. Determination of average speed of A

Total distance = 1600

Total time = 4 s

Average speed = 1600 / 4

2. Determination of average speed of B

Total distance = 1600

Total time = 18 s

Average speed = 1600 / 18

3. Determination of average speed of C

Total distance = 1600

Total time = 65 s

Average speed = 1600 / 65

4. Determination of average speed of D

Total distance = 1600

Total time = 105 s

Average speed = 1600 / 105

5. Determination of average speed of E

Total distance = 1100

Total time = 120 s

Average speed = 1100 / 120

6. Determination of average speed of F

Total distance = 500

Total time = 120 s

Average speed = 500 / 120

7. Determination of average speed of G

Total distance = 250

Total time = 120 s

Average speed = 250 / 120

8. Determination of average speed of H

Total distance = 40

Total time = 120 s

Average speed = 40 / 120

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Answer:

At the Berlin 2009 World Championships, Bolt set a world record time of 9.58 seconds for the 100m race, notching a top speed of 27.8 miles per hour (44.72 kilometers per hour) between meters 60 and 80, with an average speed of 23.5 mph.

Explanation:

Answer:

Explanation:

The force acting on an object given it's mass and acceleration can be found by using the formula

force = mass × acceleration

From the question we have

force = 75 × 3

We have the final answer as

Hope this helps you

Answer:

Chemical energy transformations take place from the outlet charger to the ringing phone.

Explanation:

chemical energy

While charging the mobile electrical energy gets transformed into chemical energy. Most of the contemporary mobile phone batteries are lithium-ion batteries where the power is saved by the chemical transformations in the ionic structure of the battery.  When the power gets into the mobile phone it is transformed and collected as chemical energy inside of the battery and when we utilize the mobile the earlier saved chemical energy is again transformed into electrical energy.

The energy transformation that takes place from the outlet charger to the

ringing phone is electrical energy from the outlet is converted to chemical

energy and back to electrical energy and sound energy when the phone is

being used and ringing.

The charger provides a source of electrical energy which gets converted to

chemical energy stored in the battery. During use, the chemical energy gets

converted to electrical energy to power the phone and to sound energy

when it rings with heat energy being dissipated also.

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Answer:

true

Explanation:

The law of conservation of mass states that in a chemical reaction mass is neither created nor destroyed. For example, the carbon atom in coal becomes carbon dioxide when it is burned. The carbon atom changes from a solid structure to a gas but its mass does not change.

Answer:

The momentum of the ball at the maximum height is zero (0 kg.m/s).

Explanation:

Given;

mass of the ball, m = 0.17 kg

initial velocity of the ball, u = 12 m/s

acceleration due to gravity, g = 9.81 m/s²

At maximum height the final velocity of the ball, v = 0

Momentum of the ball at the maximum height is given as;

P = mv

P = (0.17)(0)

P = 0 kg.m/s

Therefore, the momentum of the ball at the maximum height is zero (0).

Answer:

Sea salt is harvested by evaporating the ocean water away and generally has little to zero processing involved. Major sea salt manufacturers pump sea water into huge shallow “ponds” and allow the sun to evaporate the water... Before harvesting seawater, be sure the body of water you are using is not polluted.

Explanation:

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Given :

A mover slides a refrigerator weighing 650 N at a constant velocity across the floor a distance of 8.1 m.

The force of friction between the refrigerator and the floor is 230 N.

To Find :

How much work has been performed by the mover on the refrigerator.

Solution :

Since, refrigerator is moving with constant velocity.

So, force applied by the mover is also 230 N ( equal to force of friction ).

Now, work done in order to move the refrigerator is :

[tex]W = Force\times distance\\\\W = 230 \times 8.1\ N\ m\\\\W = 1863\ N\ m[/tex]

Hence, this is the required solution.

to get weight multiply Mass by 9.8

weight =9.8x15=147N

The force of gravity is positive 9.8m/s^2.

Answer:

50m

Explanation:

Answer: positive

Explanation: because opposites attract and north=positive and south=negative the answer should be positive.

The polarity of the red tip of the compass needle must be at the north of the earth, since it points toward the south pole of the magnet.

Polarity of a magnet is defined as the orientation of both the north and south poles of the magnet in space.

Here,

We know that, the opposite poles attract.

The magnetic needle is arranged in a such a way that, the red tip of the magnetic compass needle is actually pointing towards the geographic north pole of the earth.

In order to point the compass needle towards the magnetic south pole, the south pole of the magnet must be located in the geographic north pole.

Hence,

The polarity of the red tip of the compass needle must be at the north of the earth, since it points toward the south pole of the magnet.

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Answer:

if the tempertaure is increase it effects us very badly. it affects not only us . it effects our whole enviroment.

Answer:

Weight. Recall that the acceleration of a free-falling object near Earth's surface is approximately g=9.80m/s2 g = 9.80 m/s 2 . The force causing this acceleration is called the weight of the object, and from Newton's second law, it has the value mg.

Explanation:

Answer:

v / √2

Explanation:

A blocked from rest at the top of a hill of height h it there is negligible friction between the block and the hill, the block arrives at the bottom of the hill with speed. The block is released from rest at the top of another hill with a rough surface and height h. if one-half of the initial mechanical energy of the block Earth System is lost due to friction as the block descends the hill, the block will reach the bottom of the hill with a speed of?

Solution:

For the first block block, its potential energy at the top of the hill when it is at rest is converted to kinetic energy after release with a velocity v.

The kinetic energy = (1/2)mv², where m is the mass of the block.

For the other block placed on the top of the rough hill, the mechanical energy (kinetic energy) is halved due to the roughness of the hill. If u  is the speed of this block at the bottom of the hill then:

kinetic energy of block on the rough hill = (1//2)mu²

Hence:

(1//2)mu² = half of main system kinetic energy

(1//2)mu² = 1/2 * (1/2)mv²

mu² = (1/2)mv²

u² = (1/2)v²

u = √(v²/2)

u = v / √2

Hence the speed at the bottom of the rock of the block placed on the rough surface is v / √2