La Gravitazione

1. La figura rappresenta l'orbita ellittica di una cometa nel suo moto intorno al Sole. Il modulo dell'accelerazione centripeta è massimo nel punto:

R

G

H

T

In tutti i punti l'accelerazione ha lo stesso modulo

The correct answer is R. In an elliptical orbit, the acceleration is highest at the point closest to the Sun, which is point R. This is because the gravitational force between the Sun and the comet is strongest when they are closest to each other, resulting in a higher acceleration. At the other points in the orbit, the distance between the Sun and the comet is greater, leading to a weaker gravitational force and a lower acceleration. Therefore, the acceleration is maximum at point R.

Explanation

The correct answer is R. In an elliptical orbit, the acceleration is highest at the point closest to the Sun, which is point R. This is because the gravitational force between the Sun and the comet is strongest when they are closest to each other, resulting in a higher acceleration. At the other points in the orbit, the distance between the Sun and the comet is greater, leading to a weaker gravitational force and a lower acceleration. Therefore, the acceleration is maximum at point R.

2. La velocità di rivoluzione di un pianeta non è costante in tutti i tratti dell'orbita.

True

False

The statement is true because the velocity of a planet's revolution is not constant throughout its orbit. This is due to the planet's elliptical orbit, where it is closer to the sun at certain points (perihelion) and farther away at others (aphelion). As a result, the planet moves faster when it is closer to the sun and slower when it is farther away, causing its revolution velocity to vary throughout its orbit.

Explanation

The statement is true because the velocity of a planet's revolution is not constant throughout its orbit. This is due to the planet's elliptical orbit, where it is closer to the sun at certain points (perihelion) and farther away at others (aphelion). As a result, the planet moves faster when it is closer to the sun and slower when it is farther away, causing its revolution velocity to vary throughout its orbit.

3. Tra due oggetti, posti ad una certa distanza uno dall'altro, agisce la forza di gravità. Se vengono raddoppiate sia la massa di ciascun oggetto che la distanza alla quale si trovano, la forza gravitazionale risulta moltiplicata per un fattore pari a

1/4

1/2

1

2

4

When the mass of each object is doubled, the force of gravity between them is also doubled according to Newton's Law of Universal Gravitation. However, when the distance between the objects is doubled, the force of gravity is reduced to one-fourth of its original value. Therefore, when both the mass and distance are doubled, the force of gravity is multiplied by 2 and divided by 4, resulting in a factor of 1.

Explanation

When the mass of each object is doubled, the force of gravity between them is also doubled according to Newton's Law of Universal Gravitation. However, when the distance between the objects is doubled, the force of gravity is reduced to one-fourth of its original value. Therefore, when both the mass and distance are doubled, the force of gravity is multiplied by 2 and divided by 4, resulting in a factor of 1.

4. Un ragazzo di 50 chili che si trova sulla superficie della Terra esercita sulla Terra una forza attrattiva che, espressa in newton, è meglio approssimata da

0,00005

50

500

200000000000000

non ci sono dati sufficienti per valutarla

The correct answer is 500. The gravitational force exerted by an object on the Earth is directly proportional to its mass. Since the mass of the boy is given as 50 kg, the gravitational force he exerts on Earth can be approximated as 50 kg multiplied by the acceleration due to gravity (approximately 10 m/s^2), which equals 500 N.

Explanation

The correct answer is 500. The gravitational force exerted by an object on the Earth is directly proportional to its mass. Since the mass of the boy is given as 50 kg, the gravitational force he exerts on Earth can be approximated as 50 kg multiplied by the acceleration due to gravity (approximately 10 m/s^2), which equals 500 N.

5. L'intensità del campo gravitazionale in un punto P della superficie terrestre è uguale ...

all'accelerazione di caduta libera nel punto P

alla variazione dell'energia in uno spostamento unitario dal punto P

alla forza che agisce su un corpo posto in P

al lavoro fatto per portare una massa unitaria dall'infinito nel punto P

al lavoro fatto per portare una massa unitaria dal centro della Terra nel punto P

The intensity of the gravitational field at point P on the Earth's surface is equal to the acceleration of free fall at point P.

Explanation

The intensity of the gravitational field at point P on the Earth's surface is equal to the acceleration of free fall at point P.

6. Quale delle seguenti grandezze fisiche non necessariamente ha lo stesso valore per tutti i satelliti che sono in orbita geostazionaria intorno alla Terra?

la velocità angolare

l'accelerazione centripeta

l'energia cinetica

Il periodo orbitale

la distanza dal centro della Terra

The energy of a satellite in geostationary orbit depends on its mass and velocity. Since different satellites can have different masses and velocities, the energy kinetic may not necessarily have the same value for all geostationary satellites.

Explanation

The energy of a satellite in geostationary orbit depends on its mass and velocity. Since different satellites can have different masses and velocities, the energy kinetic may not necessarily have the same value for all geostationary satellites.

7. La forza gravitazionale esercitata dalla Terra su un grosso libro che si trova sulla cima del Gran Sasso (h=2900 m m.s.l.) ha un modulo di 20 N circa. Quale sarebbe l'intensità della forza gravitazionale della Terra sullo stesso libro se questo fosse ad un'altezza doppia rispetto al livello del mare? (Considera raggio Terra= 6370000m)

2,5 N

5 N

10 N

40 N

20 N

The gravitational force exerted by the Earth on an object is directly proportional to the mass of the object and inversely proportional to the square of the distance between the object and the center of the Earth. In this question, the height of the book is doubled, which means the distance between the book and the center of the Earth is also doubled. Since the gravitational force is inversely proportional to the square of the distance, doubling the distance will result in one-fourth (1/2^2) of the gravitational force. Therefore, the intensity of the gravitational force on the book would still be 20 N.

Explanation

The gravitational force exerted by the Earth on an object is directly proportional to the mass of the object and inversely proportional to the square of the distance between the object and the center of the Earth. In this question, the height of the book is doubled, which means the distance between the book and the center of the Earth is also doubled. Since the gravitational force is inversely proportional to the square of the distance, doubling the distance will result in one-fourth (1/2^2) of the gravitational force. Therefore, the intensity of the gravitational force on the book would still be 20 N.

8. Due leggere buste di plastica, di massa trascurabile, distano 2m. Ciascuna busta contiene 15 mele uguali. Se 10 mele vengono spostate da una busta all'altra, la forza gravitazionale tra le due buste dovrebbe...

aumentare fino a raggiungere i 3/2 del valore originale

diminuire fino a raggiungere i 2/5 del valore originale

aumentare fino a raggiungere i 5/3 del valore originale

diminuire fino a raggiungere i 5/9 del valore originale

rimanere la stessa

When 10 apples are moved from one bag to another, the mass of each bag remains the same, but the distance between the bags increases. According to the law of gravitation, the gravitational force between two objects is inversely proportional to the square of the distance between them. Therefore, as the distance between the bags increases, the gravitational force between them decreases. The correct answer states that the force will decrease until it reaches 5/9 of the original value.

Explanation

When 10 apples are moved from one bag to another, the mass of each bag remains the same, but the distance between the bags increases. According to the law of gravitation, the gravitational force between two objects is inversely proportional to the square of the distance between them. Therefore, as the distance between the bags increases, the gravitational force between them decreases. The correct answer states that the force will decrease until it reaches 5/9 of the original value.

LA Gravitazione