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Likurg_2 [28]
3 years ago
12

Mark and Sofia walk together down a long, straight road. They walk without stopping for 4 miles. At this point Sofia says their

displacement during the trip must have been 4 miles; Mark says their current position must be 4 miles. Who, if either, is correct?a)Markb)Mark, only if their starting point is the origin of a coordinate systemc)Sofia, only if their starting point is the origin of a coordinate systemd)Sofia
Physics
1 answer:
kap26 [50]3 years ago
7 0

Answer:

d) Sofia.

Explanation:

If they walked down a straight road, their displacement will be 4 miles. However, their position depends on the origin of a coordinate system which could be located anywhere. If the origin of the coordinate system was at the starting point of their walk, then and only then, you can say that their position is also 4 miles.

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Earth has four motions in its movement through space, rotation, revolution, processional, and solar motion, which two are of any
Anna007 [38]

Answer:

rotation and revolution

Explanation:

out of the four motions the earth is subject to which are: rotation about its axis, revolution around  the Sun, processional motion (a slow conical movement ) of the axis, and the solar motion (this refers to the

movement of the whole solar system with space),  only two are of any

importance to meteorology as this two causes changes in weather and seasons. The first motion is rotation. Earth rotates on its axis

once every 24 hours. One-half of the Earth’s surface is

therefore facing the Sun at all times. The second motion of Earth is its revolution around  the Sun. The revolution around the Sun and the earth tilt on its axis are responsible for changes in seasons. The Earth

makes one complete revolution around the Sun in

approximately 365 1/4 days.

6 0
3 years ago
Thinking about the winter we missed out on this year. Calvin and his tiger go sledding down a snowy hill. There is friction betw
jarptica [38.1K]

Answer:

a)  W=0, b) Work is negative, c) work is positive and scientific energy variation is positive, d)     the variation of the potential enrgy is negative,

e) total work is positive

Explanation:

Work in physics is defined by the scalar scalar product of force by displacement

          W = F. dx

The bold are vectors; this can be written in the form of the mules of the quantities

          W = F dx cos θ

where θ is the angle between force and displacement.

a) The normal force is perpendicular to the inclined plane which is perpendicular to the displacement, therefore the angle is

         θ = 90         cos 90 = 0

        W=0

In conclusion the work is zero

b) The friction force opposes the displacement whereby the angle is

       θ = 180      cos 190 = -1

        W = - fr d

Work is negative

c) To calculate the change in kinetic energy we use that the work is equal to the variation of the kinetic energy

            m g sin θ  L = ΔK

this magnitude is positive since the angle is zero cos 0 = 1

how the system starts from rest ΔK = Kf -K₀=  + Kf -0

work is positive and scientific energy variation is positive

d) change in potential energy

               The potential energy is is ΔU = Uf -U₀

we fix the reference system in the bases of the plane so Uf = 0

               ΔU = -U₀

         the variation of the potential enrgy is negative

e) The total work is formed by the work of the weight component, the work of the friction force

              W_Total = W_weight - W_roce

as the body moves down

              W_Total> 0

Therefore the total work is positive

3 0
3 years ago
When attempting to determine the coefficient of kinetic friction, why is it necessary to move the block with constant velocity
Readme [11.4K]

Answer:

Explanation:

In order to measure the coefficient of friction , we apply external force to move the body . When external force comes in motion , we adjust the external force so that it moves with zero acceleration or uniform velocity . In this case external force becomes equal to kinetic frictional force and then net force becomes zero because

net force = mass x acceleration = m x 0 = 0

Now frictional force = μ mg where μ is coefficient of kinetic friction

so F = μ mg where F is external force applied

μ = F / mg

Hence , to make external force equal to frictional force , it is necessary to make acceleration of body zero .

4 0
3 years ago
Determine the density of a rectangular piece of concrete that measures 3.7 cm by 2.1 cm by 5.8 cm and has a mass of 43.8 grams.
Novay_Z [31]
It is customary to work in SI units.

Calculate the volume of the concrete.
V = 3.7*2.1*5.8 cm³ = 45.066 cm³ = 45.066 x 10 ⁻⁶ m³

The mass is  43.8 g = 43.8 x 10⁻³ kg

The density is mass/volume.
Density = (43.8 x 10⁻³ kg)/(45.066 x 10⁻⁶ m³) = 971.9 kg/m³

Answer: 971.9 kg/m³
5 0
3 years ago
Which statements describe nuclear reactions? Check all that apply.
Alexandra [31]

Explanation:

Nuclear reactions are the reactions in which nucleus of an atom changes either by splitting or joining with the nucleus of another atom.

There are two types of nuclear reactions.

  • Nuclear fission - In this process, large atomic nuclei splits into smaller nuclei.  
  • Nuclear fusion - In this process, two small nuclei combine together to form a large nuclei.

Both nuclear fission and fusion processes involve nuclei of atoms.

For example, ^{0}n + ^{235}_{92}U \rightarrow ^{236}_{92}U \rightarrow ^{144}_{56}Ba + ^{89}_{36}Kr + 3n + 177 MeV

Thus, we can conclude that statements which are true are as follows.

  • Nuclear reactions involve the nuclei of atoms.  
  • The products of nuclear reactions are lighter than the reactants.
7 0
3 years ago
Read 2 more answers
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