Advertisements
Advertisements
Question
Different points in earth are at slightly different distances from the sun and hence experience different forces due to gravitation. For a rigid body, we know that if various forces act at various points in it, the resultant motion is as if a net force acts on the c.m. (centre of mass) causing translation and a net torque at the c.m. causing rotation around an axis through the c.m. For the earth-sun system (approximating the earth as a uniform density sphere).
Options
the torque is zero.
the torque causes the earth to spin.
the rigid body result is not applicable since the earth is not even approximately a rigid body.
the torque causes the earth to move around the sun.
Advertisements
Solution
The torque is zero.
Explanation:
As the earth is revolving around the sun in a circular motion due to gravitational attraction. The force of attraction will be of radial nature i.e., the angle between position vector r and force F is zero. So, torque = |τ| = |r × F| = rFsin0° = 0.
APPEARS IN
RELATED QUESTIONS
What happens to the force between two objects, if the mass of one object is doubled?
What happens to the force between two objects, if the masses of both objects are doubled?
Choose the correct alternative:
Acceleration due to gravity increases/decreases with increasing altitude.
Can you think of two particles which do not exert gravitational force on each other?
Let V and E represent the gravitational potential and field at a distance r from the centre of a uniform solid sphere. Consider the two statements:
(A) the plot of V against r is discontinuous.
(B) The plot of E against r is discontinuous.
A body is suspended from a spring balance kept in a satellite. The reading of the balance is W1 when the satellite goes in an orbit of radius R and is W2 when it goes in an orbit of radius 2 −R.
A tunnel is dug along a chord of the earth at a perpendicular distance R/2 from the earth's centre. The wall of the tunnel may be assumed to be frictionless. Find the force exerted by the wall on a particle of mass m when it is at a distance x from the centre of the tunnel.
A solid sphere of mass m and radius r is placed inside a hollow thin spherical shell of mass M and radius R as shown in the following figure . A particle of mass m' is placed on the line joining the two centres at a distance x from the point of contact of the sphere and the shell. Find the magnitude of the resultant gravitational force on this particle due to the sphere and the shell if (a) r < x < 2r, (b) 2r < x < 2R and (c) x > 2R.
A ball is thrown vertically upwards. It goes to a height 20 m and then returns to the ground. Taking acceleration due to gravity g to be 10 ms-2 , find :
the total time of journey of the ball .
Distinguish between gravity and gravitation
How will the force of gravitation between two objects change if the distance between them is:
Made four times
Where will you weigh more: at the moon's surface or at the earth's surface?
At what height above the earth's surface would the value of acceleration due to gravity be half of what it is on the surface? Take the radius of earth to be R.
A force can produce ________, In an object at rest. It can __________ an object and change its __________ of motion.
Why does a ball moving on a table top eventually stops?
We can shield a charge from electric fields by putting it inside a hollow conductor. Can we shield a body from the gravitational influence of nearby matter by putting it inside a hollow sphere or by some other means?
Give scientific reasons for the following:
Newton's gravitational law is the universal law of gravitation.
Ocean tides on Earth are mainly caused by ______.
The gravitational force between two objects acts in which direction?
