A student practicing for a cross country meet runs 250 m in 30 s. What is her average speed?

Cherise sets identical magnetic carts on two tracks. At the end of each track is a blue magnet that cannot move. Cherise can mov

Colt1911 [192]

Answer:

it's d

Explanation:

7 0

2 years ago

I need help :(((((((((((

Alex Ar [27]

Answer:

4- false

5- false (i think..)

Explanation:

6 0

2 years ago

(a) As you ride on a Ferris wheel, your apparent weight is different at the top and at the bottom. Explain. (b) Calculate your a

otez555 [7]

Answer:

a. The component of the net force which make up the apparent weight are added to each other at the bottom and subtracted (the centripetal force from the weight) at the top)

b. Apparent weight at the top is approximately 519.06 N

Apparent weight at the bottom is approximately 558.94 N

Explanation:

a. The apparent weight at the top is different from the apparent weight at the bottom of a moving Ferris wheel because of the opposite direction in which the centripetal force acts at the top and the bottom, which are upwards and downwards respectively, while the weight acts downwards constantly

b. The given parameters are

The radius of the Ferris wheel, r = 7.2 m

The period for one complete revolution, t = 28 seconds

The angle covered in one revolution, θ = 2·π radian

The mass of the person riding on the Ferris wheel, the passenger = 55 kg

Therefore, we have;

The angular speed, ω = Δθ/Δt = 2·π/(28)

From which we have;

Centripetal force, $F_c$ = m × ω² × r

Substituting the known values, we have $F_c$ = 55 kg × (2·π/(28 s))² × 7.2 m ≈ 19.94 N

The centripetal force, $F_c$ = 19.94 N always acting outward from the center

Weight = Mass × Acceleration due to gravity

The weight of the passenger = 55 kg × 9.8 m/s² = 539 N

The weight of the passenger = 539 N always acting downwards

At the top of the Ferris wheel the the centripetal force is acting upwards and the weight is acting downwards

Therefore;

The net force, which is the apparent weight of the passenger at the top $F_{NET_{Top}}$ = 539 N - 19.94 N ≈ 519.06 N

Apparent weight at the top ≈ 519.06 N

At the bottom of the Ferris wheel the weight is acting downwards and the centripetal force is also acting downwards

Therefore;

The net force at the bottom, which is the apparent weight of the passenger at the bottom $F_{NET_{bottom}}$ = 539 N + 19.94 N ≈ 558.94 N

Apparent weight at the bottom ≈ 558.94 N.

5 0

2 years ago

One major advantage of alternating current over direct current is that you can use alternating current with a device known as a

Oksanka [162]

transformer makes use of mutual induction for its operation in which change in magnetic field in one coil due to variation of current , induces voltage in the other coil. so changing magnetic field in the primary coil is very much needed for the transformer. Alternating current is a current which varies with time , hence it is suitable to produce changing magnetic field in the primary coil. on the other hand , the direct current remains constant all the time. hence can not produce a changing magnetic field. so DC current is not useful for transformers.

6 0

3 years ago

Read 2 more answers

ANSWER ALL QUESTIONS AND GET 100 PONTS ALONG WITH BRAINLIEST

dmitriy555 [2]

Answer:

To not exceed the 5,000 characters, see each answer with its explanation below.

Explanation:

Question 1.

A feather and a rock dropped at the same time from the same height would land at the same time when dropped by an astronaut on the moon.

The shape and mass of the feather that falls vertically down, through the air, cause the resistance of the air, that opposes the gravitational attraction of the Earth, to be considerably large, compared to the case of the rock.

This not negligible resistance of the air causes a drag on the feather that makes it fall more slowly than the rock.

Only on the moon, the almost absence of atmosphere (air) would cause the feather not to be dragged and, therefore, its acceleration will be the same as that of the rock, and both will fall with the same speed and land at the same time (there is a video in the internet that shows this experiment of the astronaut on the moon).

Question 2.

When the soccer ball is kicked, the action and reaction forces do not cancel each other out because the forces act on two different objects.

The third law of Newton, also known as the law of action and reaction, states that whenever an object experience a force (action force) from a second object, the first object will exert a force of equal size and opposite in direction (reaction force) over the second object.

Hence, the action and reaction forces act over distinct objects. The ball feels the action force (the kick) and the foot feels the reaction force from the ball; the forces do not cancel each other because they act on two different objects.

Question 3

An object is in projectile motion if it is thrown with a horizontal push.

The projectile motion is the combination of two motions: vertical motion and horizonal motion.

The vertical motion is ruled by the acceleration of gravity and will depend on both the inital vertical velocity and the acceleration of gravity.

The horizontal motion is ruled by the horizontal velocity. According with the inertia law (first law of Newton), in the absence of a horizontal force, only if the object departs with a horizontal velocity it will move horizontally.

Hence, an object can only be in projectile motion if it is thrown with a horizontal push.

Question 4

Acceleration of an object

increases as the force on the object increases.

decreases as the mass of the object increases.

is in the same direction as the force on the object.

All answers listed. ← correct answer

According to second law of Newton

$\vec{F}=m\times \vec{a}$

This is force equals mass time acceleration.

The force is a vector and the acceleration is a vector, then since mass is a positive scalar magnitude, both force and acceleration have the same direction.

Also, it is clear from the definition of force that it is proportional to both, the mass and the acceleration, then if either mass or acceleration increases (while the other remains equal) the force will increase, and if either mass or acceleration decreases (while the other remains constant) the force will decrease.

Hence, all the options are correct.

Question 5

The bowling ball will have more momentum because it has more mass.

Momentum, P, is the product of the mass (m) and the velocity (v).

$\vec{P}=m\times \vec{v}$

It is clear that the mass of the bowling ball is greater than the mass of the golf ball.

Hence, since they are moving at the same velocity, the product of the mass of the bowling ball times the velocity is greater than the product of the golf mass times the same velocity.

Question 6

An orbit is formed when an object is falling around another object, rather than into it.

An example of an object falling around another object is a rock falling in the Earth. The gravitaional pull of the Earth causes that the rock accelerates and falls vertically downward.

An example of an object falling around another object is a satellite around the Earth.

The Earth is continually pulling the satellite with vertical force and the inertia (initial velocity) of the satellite is causing it to move horizontally.

The combination of the gravitational force and the inertia cause the satellite to follow a projectile motion. When the satellite is to the correct distance it will not reach into the Earth but will continually move around the Earth following a circular path named orbit.

Question 7

When the force of gravity is matched by the force of air resistance, an object can reach terminal velocity (two word answer).

When the force of gravity matches the force of air resistance, the net force on the falling object is zero.

Hence, as per the second Law of Newton, force equals the product of the mass and the acceleration, the acceleration is also zero.

Zero acceleration means constant velocity.

That constant velocity is a limit or maximum for the velocity that an object can reach when falling and is called terminal velocity.

3 0

2 years ago