PHYSICS
HIGH SCHOOL

Answer:

Answer:

Conditioned stimuli

Explanation:

Due to jack always taking soda whenever he hangs out with his friends, his nervous system has been conditioned to associate the presence of his friends to taking soda. This means that his body system will start to interprete the presence of his friend as a stimulus to prompt him to drink, and the natural way his body can make him want to drink is by initiating the thirst reactions. On this particular day, Jack seeing his friend was perceived by his body as time for a drink so he became thirsty.

MIDDLE SCHOOL

What is the momentum of a dog of mass 20 kg that is running east with a speed of 3 m/s?

Answer:

60 kg.m/s

Explanation:

Momentum is the product of mass and velocity

p=m*v where m is mass in kg and v is velocity in m/s

Given that;

m=20kg and v=3m/s then;

p= 20×3= 60kgm/s

Answer:

60 kg * m/s east.

Explanation:

Momentum is a vector quantity, so you must include direction in the answer. Work by the guy above me ^_^

MIDDLE SCHOOL

A 55.0-kg skydiver free falls for a period of time before opening his parachute. What is his kinetic energy when he reaches a velocity of 16.0 meters/second? 7,040 J

440 J

539 J

cannot be determined without knowing his height above the ground

Given:

Mass of the skydiver:55 Kg

Velocity of the skydiver (v): 16m/s

Kinetic energy= 1/2mv^2

Kinetic energy= 1/2(55x16x16)

Kinetic energy= 7040J

MIDDLE SCHOOL

How do the atoms of a molecule stay together? A.

chemical bonds

B.

magnetic force

C.

attraction of electrons and neutrons

D.

through physical changes

The answer is A. Atoms in molecules are held together with chemical bonds.

HIGH SCHOOL

A car traveling due east at 20 m/s reverses its direction over a period of 10 seconds so that it is now traveling due west at 20 m/s. What is the direction of the car’s average acceleration over this period?

Answer:

west

Explanation:

We can take east as positive (+) direction and west as negative (-) direction. With this sign convention, we have:

- Initial velocity: u = +20 m/s (due east)

- Final velocity: v = -20 m/s (due west)

- Time taken to change velocity: t = 10 s

Therefore, we can use the formula for the acceleration to calculate the car's acceleration:

And the negative sign means the direction of the car's acceleration is west.

COLLEGE

What is the potential difference between the plates when the charge on the capacitor plates is 4.0 μC ?

Answer:

Explanation:

We are given that

The separation between parallel plate capacitor=d=0.81 mm=

Area =A=

Dielectric constant k=2.1

Charge on parallel plate capacitor=

We know that

Where

Substitute the values

Hence, the potential difference between the plates =

HIGH SCHOOL

An object is acted upon by a constant force which gives it a constant acceleration a. At a certain time t1, having started from rest at t = 0, it has kinetic energy K1. At what time t2 has its kinetic energy doubled?

Answer:

Explanation:

The kinetic energy of a body is that energy it possesses due to its motion. In classical mechanics, this energy depends only on its mass and speed, as follows:

The speed in an uniformly accelerated motion is given by:

Replacing this expression in the formula for the kinetic energy, we have:

So, if we have :

Equaling (1) and (2) and solving for :

MIDDLE SCHOOL

What is the acceleration of a body revolving in a circle at uniform speed? A. The acceleration is zero.

B. The acceleration is directed tangentially.

C. The acceleration is directed toward the center.

D. The acceleration is directed away from the center.

The acceleration is directed towards the centre when a body revolving in a circle at uniform speed.

Answer: Option C

Explanation:

When an object w=is moving with an uniform speed, its acceleration will be constant because acceleration depends upon the velocity of the object. Also due to circular motion, the acceleration is directed towards the center point. The tangential component of the acceleration tend to be constant in this zero.

The acceleration of a body revolving in a circle at uniform speed is directed toward the center. (C) It's called "centripetal acceleration".

COLLEGE

Recall some things you already know about projectile motion. Does a force in the vertical direction affect the horizontal component of an object’s velocity? In this situation, can you use the horizontal velocity component to find the time required to travel some horizontal distance?

Answer:

vertical force cannot change the velocity on the x-axis. t =x/v₀ₓ

Explanation:

The force is a vector magnitude, so the forces on the x-axis affect the acceleration on this axis. Consequently a vertical force cannot change the velocity on the x-axis.

= m g

Fₓ = 0

The horizontal velocity in projectile motion is constant, if we neglect the air resistance, so it can be used to find the time of a horizontal displacement

x = v₀ₓ t

t =x/v₀ₓ

The only magnitude that is the same for both movements is the time that is a scalar

MIDDLE SCHOOL

The model of the universe that suggests that the sun is the center of the universe was first brought by

The answer is Nicolaus Copernicus

Copernicus was the first person to suggest that the Earth revolved around the sun.