PHYSICS
MIDDLE SCHOOL

Answer: - Weightlessness, condition experienced while in free-fall, in which the effect of gravity is canceled by the inertial force resulting from orbital flight. The term zero gravity is often used to describe such a condition.

OR

- Weightlessness is a situation in which the effective weight of the body becomes zero. Example 01: When a body is lying in a freely falling lift, then acceleration, a = g. So, the effective acceleration due to gravity in the left. g'=g–a⇒g'=g−g=0.OR

- Weightlessness is the complete or near-complete absence of the sensation of weight. This is also termed zero-G, although the more correct term is "zero G-force". It occurs in the absence of any contact forces upon objects including the human body.OR

- The sensation of weightlessness, or zero gravity, happens when the effects of gravity are not felt. Technically speaking, gravity does exist everywhere in the universe because it is defined as the force that attracts two bodies to each other. But astronauts in space usually do not feel its effects.OR

- Weightlessness of a body is the state in which the body experiences that the body is not being attracted by any force.THANKS
HIGH SCHOOL

A mass hanging from a spring undergoes vertical simple harmonic motion. 1) Where in the motion is the velocity equal to zero?

At the point where the spring is unstretched.

At the highest point in the oscillation.

At the lowest point in the oscillation.

At the point half-way between the highest point and the lowest point.

Answer: the velocity is zero at the following points

1. At the highest point in the oscillation.

2. At the lowest point in the oscillation.

Explanation:

HIGH SCHOOL

Two lovers are parked 10.0m from the edge of a cliff in a car whose mass, including that of the occupants is 100kg. A jealous suitor ties a rope to the car's bumper and a 50. kg rock to the other end of the rope. He then lower the rock over the edge of the cliff, and the car, which is in neutral, accelerates toward the edge. b) What is the acceleration of the car towards the edge?

c) How long do the lovers have to apply the brakes before they go over the edge?

I will solve this assuming: the rock is lowered at constant speed; the surface is level, and there is no friction

then, the tension in the rope equals the weight of the rock, so T= 50kg x 9.8m/s/s

T=490N; this is the tension in the rope and the force that pulls on the car, so we have

F = ma => a=F/m=490N/1000kg = 0.49m/s/s

if you are initially at rest and accelerate at 0.49m/s/s, it will take a time given by

dist = 1/2 at^2 => t=sqrt[2d/a] to travel 10 m:

t=sqrt[2x10m/0.49m/s/s] = 6.4s which is the time they have to react.

then, the tension in the rope equals the weight of the rock, so T= 50kg x 9.8m/s/s

T=490N; this is the tension in the rope and the force that pulls on the car, so we have

F = ma => a=F/m=490N/1000kg = 0.49m/s/s

if you are initially at rest and accelerate at 0.49m/s/s, it will take a time given by

dist = 1/2 at^2 => t=sqrt[2d/a] to travel 10 m:

t=sqrt[2x10m/0.49m/s/s] = 6.4s which is the time they have to react.

Hello there.

c) How long do the lovers have to apply the brakes before they go over the edge?

6.4s

c) How long do the lovers have to apply the brakes before they go over the edge?

6.4s

HIGH SCHOOL

What is the celestial sphere? A. The celestial sphere is a representation of how the entire sky looks as seen from Earth.

B. The celestial sphere is a model that shows the true locations in space of the Sun and a few thousand of the nearest stars.

C. The celestial sphere is a model of how the stars are arranged in the sky relative to our Sun, which is in the middle of the sphere.

D. It represents a belief in an Earth-centered universe, and hence is no longer considered to have any use.

Answer:

A. The celestial sphere is a representation of how the entire sky looks as seen from Earth.

Explanation:

The celestial sphere is an imaginary sphere that has an arbitrarily large radius and is concentric to the earth. It is an abstract spherical shell formed by the sky usually represented as an infinite sphere, the center of which is a given observer's position (earth). It's represents how the sky looks from the observer's position (Earth).

HIGH SCHOOL

Three cars, car X, car Y and car Z, begin accelerating from rest,at the same time. Car X is more massive than car Y, which is moremassive than car Z. The net force exerted on each car is identical.After 10 seconds, which car has the most amount of momentum?A) They all have the same amount of momentumB)Car ZC)Car YD)Car X

Answer:

A) They all have the same amount of momentum

Explanation:

Newton's second law of motion gives an operational definition of force as the rate of change in momentum. It states that the rate of change in momentum of a body is directly proportional to the applied force.

This is expressed as follows mathematically;

We can further simplify (1) above as follows;

if initial velocity u = 0, then equation (2) becomes

This implies that change in momentum is equal to the impulse experienced by the body.

According to the problem stated, all the cars X, Y and Z are subjected to the same magnitude of force for the same time interval, hence irrespective of their masses they will all experience the same magnitude of change in momentum. Also, since they all began from rest, their velocities may differ as a result of their differences in mass, however their instantaneous momenta at end of the 10s will be the same.

The condition that would have warranted different momenta for them is if they had different initial velocities.

When different masses with a common initial velocity are subjected to the same magnitude of force for the same time interval, they will experience the same momentum at the end of the time interval although with different velocities. The smallest mass will have the highest velocity while the largest will have the lowest velocity at the end of the time interval.