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anastassius [24]
2 years ago
9

A father is trying to teach his child to ice skate. As the child stands still, the father pushes him forward with an acceleratio

n of 2.0 m/s2 north. If the child's mass is 20 kg what is the force with which the father is pushing
Physics
1 answer:
rjkz [21]2 years ago
4 0

Hi there!

We can use Newton's Second Law:

\Sigma F = ma

∑F = net force (N)

m = mass (kg)

a = acceleration (m/s²)

We are given the mass and acceleration, so:

∑F = 20 · 2 = <u>40 N</u>

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Please, help!!
pashok25 [27]

Answer:

The net force in the middle particle is zero, and it has no direction.

Explanation:

First, the force that one charge does in other charge is:

F = K*q1*q2/r^2

where k is a constant, q1 and q2 are the charges, and r is the distance between the charges.

If the force is positive, the force is repulsive (pushes away the charge) if the force is negative, is attractive.

Now, we have that the middle charge has a charge of 4.00nC, and in each side at a distance of 4m, has a charge of 4.00nC.

i will write qL as the charge in the left, qR as the charge in the right, and qM as the charge in the middle.

The force that the charge in the right does to the charge in the middle is:

Fr = (k*(4.00nC)^2)/4m^2 = k*(nC/m)^2

And is positive, so this is a repulsive force, this means that if the charge is at the right of the middle charge, then this force pushes the middle charge to the left.

For the left charge we have the same:

Fl = (k*(4.00nC)^2)/4m^2 = k*(nC/m)^2

But in this case, the force pushes the particle to the right, then this force, that is equal in magnitude to the previous force, pushes it in the opposite direction, then the total force in the middle particle is anulated. This is because the two external particles are "pushing" the middle particle with the same force and in the opposite direction.

6 0
2 years ago
Why should you never use the coarse adjustment on high power
umka21 [38]

Answer:

First, the image moves in and out of focus too quickly, so that it is difficult to precisely adjust the focus. Second, you run the risk of crashing the objective into the slide. Use the coarse focus only with the 4x low power objective. You can use the fine focus knob with all objectives.

Explanation:

3 0
3 years ago
Lithium has 3 protons. how many neutrons are in the isotope lithium -8
Oksi-84 [34.3K]

Answer:

5 neutrons

Explanation:

Both protons and neutrons have a mass of about 1 atomic mass unit (amu). The number in the notation for an isotope is its mass in amu. That means the number is essentially the sum of protons and neutrons in the isotope (electrons don't contribute significantly to the mass).

If lithium has 3 protons, lithium-8 has 8 - 3 = 5 neutrons.

3 0
3 years ago
Read 2 more answers
A 3,220 lb car enters an S-curve at A with a speed of 60 mi/hr with brakes applied to reduce the speed to 45 mi/hr at a uniform
Grace [21]

The magnitude of the total friction force exerted by the road on the tires at B will be 919.46 lb.

<h3>What is the friction force?</h3>

It is a type of opposition force acting on the surface of the body that tries to oppose the motion of the body. Its unit is Newton (N).

Mathematically, it is defined as the product of the coefficient of friction and normal reaction.

The given data in the problem is;

The weight is,W= 3,220 lb

The speed is,u= 60 mi/hr

The reducing speed is,v= 45 mi/hr

The distance traveled is,d= 300 ft

The radius of curvature of the path of the car at B is,R= 600 ft.

1 mile = 5280 ft

From the Newtons' equation of motion;

\rm v^2 = u^2 +2ad \\\\ \rm (45 \times \frac{5280}{3600} )^2 = (60 \times  \frac{5280}{3600}  )^2 +2a\times 300 \\\\

The tangential accelerations are;

\rm a_t = \frac{66^2 -88^2}{600} \\\\ \rm a_t =  -5.65 ft/sec^2 \\\\

The force is found as;

\rm \sum F = ma \\\\ \frac{3220}{32.2} \times -5.65 \\\\ F_T= 565 \ lb

The normal force  is;

\rm F_n = \frac{3220}{32.2} \times \frac{66^2}{600} \\\\ F_N =726 \ lb

The net or the total friction force exerted by the road on the tires at B. is found as;

\rm F = \sqrt{(565)^2+(726)^2} \\\ F = 919.946 \ lb

Hence, the magnitude of the total friction force exerted by the road on the tires at B will be 919.46 lb.

To learn more about the friction force, refer to the link;

brainly.com/question/1714663

#SPJ1

6 0
1 year ago
What is meant by fundamental unit? write any two difference between mass and weight.​
yulyashka [42]

Answer:

Fundamental unit is any unit that is not dependent on other units and other units can be derived from them

Explanation:

Units such as Kilogram, Mass and Time are said to be fundamental units because they are independent.

Differences between Mass and weight;

1. Mass is the measure of the amount of matter in a body while weight is a measure of how the force of gravity acts upon that mass.

2. Mass is a scalar quantity while weight is a vector quantity

8 0
2 years ago
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