which of the following is a contact force?

a. gravity
b. magnetic force
c. air resistance
d. electrical force

Answer:

Heavy objects fall at the same rate (or speed) as light ones. The acceleration due to gravity is about 10 m/s2 everywhere around earth, so all objects experience the same acceleration when they fall.

Explanation:

normal force=mass*gravitational force

normal force=40*0

normal force=40

Answer:  71.43 kilograms

This value is approximate rounded to two decimal places.

=====================================================

Explanation:

The ground is pushing up with a normal force of 700 N. Because the box is sitting still, this means the force of gravity is pulling the box down with a force of 700N to keep things balanced.

If the force of gravity was greater than 700N, then the box would fall through the ground. If the force of gravity was smaller than 700N, then the box would be accelerated upward. Since neither event is happening, the force of gravity must be equal to the normal force.

Now turn to Newton's second law which says

F = ma

where F is the force, m is the mass and 'a' is the acceleration. We're given the acceleration of gravity is roughly 9.80 m/s^2. So a = 9.80

The force we'll plug in is F = 700. The value of m is unknown, but we can solve for it as such

F = ma

700 = m*9.80

700 = 9.08m

9.80m = 700

m = 700/9.80

m = 71.4285714285714

m = 71.43

The mass is roughly 71.43 kilograms.

Answer:

once a week

Explanation:

once a week so answer B

Answer:

B-Once a week

Explanation:

You answer is B-Once a week

Answer: True

Explanation: I got it right on my test :)

Answer:

0.26

Explanation:

Given that :

Diameter of ball = 3.81 cm = 3.81/100 = 0.0381 m

Radius (r) = 0.0381 / 2 = 0.01905 m

Average density of ball (Db) = 0.0842 g/cm³ = (0.0842 / 1000)kg / 10^-6 = 0.0842/ 1000 * 10^6 = 84.2kg/m³

Density of water (Dw) = 1000kg/m³

Volume of hollow ball: (4/3) * pi * r³

V = (4/3) * π * 0.01905^3

V = 0.0000289583 m³

Required force = (Dw * V * g) - (Db * V * g)

= (1000 * 0.0000289583 * 9.8) - (84.2 * 0.0000289583 * 9.8)

= 0.259896109172

= 0.2598 N

To determine the force that must be applied to the hollow ball to hold it stationary while it is completely submerged under water is 0.2243 Newton.

Given the following data:

Density of water = 1000 [tex]kg/m^3[/tex]

Conversion:

Diameter of hollow ball = 3.81 centimeters to meters = [tex]\frac{3.81}{100} = 0.0381\;m[/tex]

Density of hollow ball = 0.0842 [tex]g/cm^3[/tex] to [tex]kg/m^3[/tex] = [tex]\frac{0.0842 \times 10^6}{1000} = 84.2 \;kg/m^3[/tex]

To determine the force that must be applied to the hollow ball to hold it stationary while it is completely submerged under water:

First of all, we would calculate the volume of the hollow ball by using the formula:

[tex]Volume = \frac{4}{3} \pi r^3\\\\Volume = \frac{4}{3} \times 3.142 \times 0.01905^3\\\\Volume = 4.19 \times 0.0000069\\\\Volume = 0.000029 \;m^3[/tex]

Next, we would find the force required for water and the hollow ball:

For water:

[tex]F_w = D_wVg\\\\F_w = 1000 \times 0.000029 \times 9.8\\\\F_w = 0.2842\; Newton[/tex]

For hollow ball:

[tex]F_h = D_hVg\\\\F_h = 84.2 \times 0.000029 \times 9.8\\\\F_h = 0.0239\; Newton[/tex]

Now, we can find the force that must be applied to the hollow ball:

[tex]Force = F_w - F_h\\\\Force = 0.2482 - 0.0239[/tex]

Force = 0.2243 Newton

Read more: https://brainly.com/question/18320053

Answer:

[tex]\huge\boxed{\sf T = 2.04\ secs}[/tex]

Explanation:

Given Data:

Initial Velocity = [tex]\sf V_{i}[/tex] = 20 m/s

Angle = [tex]\sf \theta[/tex] = 30°

Acceleration due to gravity = g = 9.8 m/s²

Required:

Time of flight = T = ?

Formula:

[tex]\sf T = \frac{2\ V_{i}\ sin\theta}{g}[/tex]

Solution:

Putting values in the above formula

T = 2(20)sin 30 / 9.8

T = 40 (0.5) / 9.8

T = 20 / 9.8

T = 2.04 secs

[tex]\rule[225]{225}{2}[/tex]

Hope this helped!

Answer:

I think it a

Explanation:

Answer:

c

Explanation:

Answer:

Cohesion

Explanation:

Surface tension of water refers to the ability of the surface of water as a liquid to resist an external force. Surface tension of a liquid like water is dependent on the force of attraction that hold its molecules to one another, which is a force called COHESIVE FORCE.

Cohesion is a property of water characterized by the ability of water molecules to be attracted to one another. This cohesive property causes its molecules to be able to resist external forces or in other words is responsible for the SURFACE TENSION. Hence, the stronger the cohesive force between molecules of a liquid, the higher the surface tension.

Answer:

you can use a balance

Explanation:

when you tend to measure something you are using your brain so why dont you use your brain dimwitt

Answer:

22 kg

Explanation:

I hope this helps!

Answer:

22 kilograms

Hope it helps :) (if it does can i pls have brainliy thing)

Answer:

wind has two important things that is direction and speed.

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 = 6500 × 0.3

We have the final answer as

Hope this helps you

Answer:

True

Explanation:

Answer:

The atomic mass of an atom that has 5 protons and 7 neutrons would be 12.

Explanation:

In all cases, the number of protons added to the number of neutrons equate to the mass of an atom. Electrons do have mass, but it's so miniscule and insignificant that it doesn't contribute to the overall mass of the atom, so there's no need to count them.  

Bonus Information:

DO NOT CONFUSE MASS WITH CHARGE! Protons and neutrons are the only particles that contribute to the mass of an atom. Meanwhile, protons (+) and electrons (-) are the only particles that have a charge. As it says in its name, neutrons are neutral or have no charge.

Remember:

C = p - e

M = p + n

C = atomic charge, M = atomic mass, p =protons, n = neutrons, e = electrons

I hope this helps!

Answer:

D

Explanation:

because all are reffering to the answer you need

Answer:

the graph represents an endothermic reaction

Explanation:

remember:

endo- inside

exo- out

simple methods to carry a sufferer encompass the four-hand seat, backpack carry, ski pole or tree limb backpack carry, and coiled rope seat. In the first method, two rescuers interlock hands. Each rescuer first grasps his right wrist with his left hand.

Answer:

C is corret answer okay

Answer:

The average speed of an object is defined as the distance traveled divided by the time elapsed. Velocity is a vector quantity, and average velocity can be defined as the displacement divided by the time.

Answer:

Speed = 0.5 m/s

Explanation:

Time = 3min = 180 seconds

Distance = 90 meters

[tex]Speed =\frac{Distance}{Time} \\\\Speed= \frac{90}{180} \\\\Speed = \frac{1}{2} \\\\Speed =0.5\:m/s[/tex]

Answer:ttttrsc

Explanation:eeeeee

Answer:

1200

Explanation:

Answer:

The time it takes for the jet to reach landing speed is approximately 0.136 hours which is approximately 489 seconds

The landing speed is approximately 466.365 km/hr

Explanation:

The given parameters are;

The initial cruising speed of the jet = Mach 0.79 = 844 km/hr

The rate of speed reduction in the last 89 km = -2780 km/hr²

The distance it  takes the jet to reduce its speed for landing = 89 km

Given the above information,  we make use of the following equation of motion;

s = u·t - 1/2·a·t²

v² = u² - 2·a·s

Where;

s = The distance over which the acceleration (deceleration) is applied = 89 km

u = The initial velocity = 844 km/hr

t = The time taken for the accelerating/decelerating motion

v = The final velocity (landing speed)

Substituting the values gives;

v² = 844² - 2·(2780)·89 = 217496

v = √217496 = 466.365 km/hr

v ≈ 466.365 km/hr

Therefore, the landing speed, v  ≈ 466.365 km/hr

The time it takes is given by the equation, v = u - a·t

Therefore;

t = (u - v)/a = (844 - 466.365)/2780 ≈ 0.136 hours

The time it takes for the jet to reach landing speed ≈ 0.136 hours

From, s = u·t - 1/2·a·t², we have

89 = 844·t - 1/2 × 2780 × t²

89 = 844·t - 1390 × t²

1390 × t² - 844·t + 89 = 0

Solving with an online application gives;

t = 211/695 + (√(27187/2))/695 = 0.4715 hours or t = 211/695 - (√(27187/2))/695 = 0.136 hours

We note that the second time is for the time it will take the jet to get back to 89 km after reaching a speed of 0

Therefore, the correct time is t = 0.136 hours

The time it takes for the jet to reach landing speed ≈ 0.136 hours

Answer:

Photosynthesis is the process of using water, carbon dioxide and sunlight to produce sugar. The process of photosynthesis requires specialized cellular structures called chloroplasts to capture energy from the Sun and converted into chemical energy.

Explanation:

Power quotient of : _____?

Answer :

[tex]p = \frac{w}{t} [/tex]

P is Power (Watt)

W is Work (Joule)

T is Time (second)

So, it means Work and Time is the quotient of Power. (B)

Answer:

2.46

Explanation:

From the question given above, the following data were obtained:

Critical angle (C) = 24 °

Refractive index (n) =?

The refractive index of the diamond can be obtained by using the following formula as illustrated below:

Refractive index (n) = 1 / sine [critical angle (C)]

n = 1/sine C

n = 1 / sine 24 °

n = 1/0.4067

n = 2.46

Thus, the refractive index of the diamond is 2.46

Answer:

The correct answer is B

Answer:

thats a lot, which one u want me to do?

Explanation: