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pochemuha
3 years ago
5

Plz help me. I need urgent Why a magnetic compass is used to determine direction? Why a nail gets magnetized when kept close to

magnet? Why two pins get attracted by bar magnet maintain distance between ends?
Physics
1 answer:
docker41 [41]3 years ago
4 0

Answer:

Compasses are mainly used in navigation to find direction on the earth. This works because the Earth itself has a magnetic field which is similar to that of a bar magnet. The compass needle aligns with the Earth's magnetic field direction and points north-south. Also, In a magnet all the domains are oriented in the same direction. In the case of a nail, the domains can be aligned in the same direction causing the nail to become magnetic. That is because if you hang a bar magnet from a thread, the north pole will point to magnetic north. When you bring one north pole close to another north pole they repel each other. You can feel the two magnets pushing each other apart.

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1) Little Timmy wants to measure how tall his house is. He doesn’t have a tape measure but does have a stopwatch. He recruits Bi
kifflom [539]

1) 13.7 m

The motion of the rock is a free fall, with constant acceleration g=9.8 m/s^2 towards the ground, so the total distance it covers is given by the SUVAT equation:

S=\frac{1}{2}gt^2

where S is the height of the house, and t is the time the rock takes to reach the ground. Substituting t=1.67 s, we find:

S=\frac{1}{2}(9.8 m/s^2)(1.67 s)^2=13.7 m

2) 105.5 m

The motion of the stuffed chicken is a projectile motion, with a uniform horizontal motion (with constant velocity of v=36.0 m/s) and a vertical accelerated motion (with constant acceleration of g=9.8 m/s^2).

First of all, we can find the total time of the ball by considering the vertical motion only. We know the vertical distance covered, S=42.2 m, so the time of the fall is

S=\frac{1}{2}gt^2\\t=\sqrt{\frac{2S}{g}}=\sqrt{\frac{2(42.2 m)}{9.8 m/s^2}}=2.93 s

And now we can consider the horizontal motion to find the horizontal distance covered by the stuffed chicken:

d=vt=(36.0 m/s)(2.93 s)=105.5 m

3) 49.4 m

Again, the motion of the ball is a projectile motion, with a horizontal motion and a vertical motion.

The range of a projectile launched from the ground can be found by using the formula:

d=\frac{v^2}{g} sin 2 \theta

where, in this case:

v = 22.0 m/s is the initial velocity

\theta=45^{\circ}

Substituting into the formula, we find

d=\frac{(22.0 m/s)^2}{9.8 m/s^2}(sin (2\cdot 45^{\circ}))=49.4 m

4) 9.6 m/s^2

The frictional force acting on the monkey is given by:

F_f = \mu mg=(0.16)(31.0 kg)(9.8 m/s^2)=48.6 N

where \mu is the coefficient of friction and m is the mass of the monkey.

We have two forces acting on the monkey: the push of F=345 N and the frictional force acting in the opposite direction. According to Newton's second law, the net force will be equal to the product between the monkey's mass and its acceleration, so we can find the acceleration:

F-F_f=ma\\a=\frac{F-F_f}{m}=\frac{345 N-48.6 N}{31.0 kg}=9.6 m/s^2

5) 462.3 N

The horizontal component of the pushing force is:

F_x = F cos \theta = (648 N)(cos 25^{\circ})=587.3 N

The frictional force, acting in the opposite direction, is

F_f = \mu mg=(0.17)(75.0 kg)(9.8 m/s^2)=125.0 N

where \mu is the coefficient of friction and m is the mass of the box.

The net force on the box is therefore given by the net force on the horizontal direction:

F_{net}=F_x -F_f=587.3 N -125.0 N=462.3 N

6) 89.5 N

First of all we need to calculate the total weight of the table and the items above it.

The weight of the table is:

W=mg=(25.0 kg)(9.8 m/s^2)=245 N

So the total weight of the table and the items is

W=245 N+63 N+12 N+44 N+24 N+9N+10N=407 N

The force needed to get the table moving must be at least equal to the frictional force, which is equal to the product between the coefficient of friction and the weight of the all stuff:

F=F_f = \mu W=(0.22)(407 N)=89.5 N

7 0
3 years ago
The following table lists the work functions of a few commonmetals, measured in electron volts.
steposvetlana [31]

Answer:

Lithium

Explanation:

The equation for the photoelectric effect is

\frac{hc}{\lambda}= \phi + K_{max}

where

\frac{hc}{\lambda} is the energy of the incident photon, with

h being the Planck constant

c is the speed of light

\lambda is the wavelength of the photon

\phi is the work function of the metal (the minimum energy needed to extract the photoelectron from the metal)

K_{max} is the maximum kinetic energy of the emitted photoelectrons

In this problem, we have

\lambda= 190 nm = 1.9\cdot 10^{-7}m is the wavelength of the incident photon

K_{max}=4.0 eV is the maximum kinetic energy of the electrons

First of all we can find the energy of the incident photon

E=\frac{(6.63\cdot 10^{-34} Js)(3\cdot 10^8 m/s)}{1.90\cdot 10^{-7} m}=1.05\cdot 10^{-18} J

Converting into electronvolts,

E=\frac{1.05\cdot 10^{-18} J}{1.6\cdot 10^{-19} J/eV}=6.6 eV

So now we can re-arrange the equation of the photoelectric effect to find the work function of the metal

\phi = E-K_{max}=6.6 eV - 4.0 eV=2.6 eV

So the metal is most likely Lithium, which has a work function of 2.5 eV.

3 0
3 years ago
State how heat loss by radiation is minimized in a thermos flask​
Verdich [7]
Thermos bottles are equipped with the parts that can prevent the hot water from cooling down by the three ways: Supporting the inner container by a few heat-insulating supporters to minimize the heat loss through heat conduction, using a vacuum space between the outer and the inner vessels to eliminate the heat loss by the air convection, and giving a high reflectivity to the inner surface of the outer vessel and the whole surface of the inner container to reduce the heat loss due to the radiation cooling.
7 0
2 years ago
A coal - fired power station produces 100MJ of electrical energy when it is supplied with 400MJ of energy from its fuel. The eff
Alexus [3.1K]

Answer:

100 divide by 400 times 100 percent

8 0
3 years ago
The principles of magnetism apply everywhere on earth. What does this tell us about God and His character?
Bas_tet [7]

Answer:

God is omnipresent.

Explanation:

This means God is everywhere and He works where ever we are in the world

3 0
3 years ago
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