1)why is it that when a ball is dropped,even though it has a zero horizontal speed,it falls?

Question

just near you on a moving boat?

2)even though there is a large force exerted on us by the sun why aren't we pulled towards it?.

3) even though earth is a non inertial frame of reference why don't we feel any force when it turns on the circular motion around the sun? help required please

Answer 1

1/ Because it has no horizontal speed (with respect to the boat), it is expected to fall like that, near the boat, even if the boat moves 100 km an hour. If it fell far away from the boat, that would be paradoxical, because it had moved away from the boat without an initial horizontal speed. That is the point of view of an observer on the boat.

To a man on the ground, the ball does move horizontally, because when released, it has the same horizontal speed as the boat. Therefore it will go side by side with the boat until it touches the water if air resistance is negligible.

2/We aren't pulled toward the sun because the earth pulled us back. Even though the sun has very large mass, its distance to us is also gigantic as compared to a mere 6400 km distance from the center of the earth. And you know that the pull is inversly proportional to the square of the distance.

3/Again, the pull of the earth is very large in comparison with the force due to its slow revolution around the sun. If the earth revolved around the sun once a month, maybe we would feel that force.

Answer 2

1)because it has vertical velocity due to earth's gravity

2)because earth's gravity also pulls the sun towards us

3)we don't feel any force because it is balanced

Answer 3

You would better post three questions for this. But anyway...

1. This is due to Galilean invariance. A revolutionary principle first described 1632 by Galileo Galilei. The laws of nature don't depend on the reference frame: If you are standing still on fixed ground, a ball dropped with zero horizontal speed will fall just near you. The same thing happens if you stand in a train or a boat.

If you view the event from outside the train, you will say that the ball does not have zero horizontal speed, it has the same speed as the train.

2. We are pulled toward the sun, but we don't come closer to the sun. The earth orbits the sun. Suppose the sun would not pull earth, then earth would move on a straight line. Due to the sun's gravity, earth's path is curved.

The force needed to keep an object on a curved path is the centripetal force. Gravity is just this centripetal force and therefore earth does not drop down to sun.

3. In the accelerated frame of earth the sun's gravity is balanced by centrifugal force. The rotation on the other hand is too slow to notice directly. You might notice it with a device like the Foucault pendulum.

Answer 4

Newton's First law of motion defines law of nertia , ie. body in steady state tries to remain steady and body in motion continue to remain in motion.

Newton's second Law of motion in simple way states that change in direction of motion needs application of external force.

New direction of motion depends on magnitude and direction of force applied.  

Answer 5

1. Let me first clarify what I understand from the question.

On a moving boat, even though the horizontal speed is zero, when a ball is dropped, it falls near you.

Answer:

Ball falls because of the gravitational pull of the earth.

Answer 2: As per the "inverse-square law" some physical quantity or strength is inversely proportional to the square of the distance from the source of that physical quantity. Since the distance of sun is far more than that of earth from us, we are not pulled away by Sun.

Answer 3: We can consider ourself as Geostationary. We actually feel a lot of force but get adjusted to it pretty soon. In very same fasion, when we get out of a swimming pool, we feel very heavy, almost unable to lift our own weight, however, in a few minutes, we get adjusted.

HIH

Answer 6

1. The ball in the moving boat does have a speed of the boat.

For the person in the boat the ball falls vertically down whereas for a person outside the boat the ball follows a parabolic path, a downward vertical accelerated motion and a horizontal velocity, same as that of the boat.

2.

Because of the large force exerted by the sun and the large velocity of earth in a perpendicular direction to the radius joining the earth and sun, the earth moves along a circular path (to be exact in an elliptical path). But for this velocity the earth will move straight to the center of the sun.

3.

Only in the inertial frame of reference, one can feel an external force. In a non inertial frame of reference, newton laws will be valid only  if we add pseudo forces to make it inertial frame.

Answer 7

1.Are u trying to ask that when u r on amoving boat with a ball then even though the bal didnt hav horizontal speed instead of falling xactly vertically why does it fal near u? Well this is because its not the ball that moves horizontally.In the time interval during which u release the ball and the ball falls on the boat ,the boat as well as u hav covered a horizontal distance .That is the ball doesnt move away frm u but u move away frm the ball due to the ball's horizontal speed.

2.The gravitational pull of the sun supplies the necessary centripetal force to the earth to move around the sun in the orbit,ie,all the pull is utilised by the earth in revolving and no extra pull exists.

3.Same as above

Answer 8

1)when you are riding the boat holding a ball, the ball itself (and you) are moving with the boat, so it has horizontal speed. picture yourself watching a person on a boat carrying a ball.. does it stay still compared to you? Same would happen if you dropped the ball from a moving car, if it wasn't for the air resistance.

1) we are, as well as with the earth, orbiting the sun. we have the same tangential velocity than the earth itself, enough to keep us in a stable orbit

3) we are orbiting the sun also, so the very force that keeps the earth from moving in a straight line, tangencial to its orbit, keeps us from feeling any force as the earth keeps turning sideways in orbit with the sun.

you must remember: doesn't matter what we are (a ball, a person) or what we are riding (a boat, the planet earth), the forces of gravity from an external body & inertia from moving at a certain speed still applies to us.

Answer 9

1)why is it that when a ball is dropped,even though it has a zero horizontal speed,it falls just near you on a moving boat?

  Because it does have horizontal velocity, it is moving with the boat.

2)even though there is a large force exerted on us by the sun why aren't we pulled towards it?.

  We, the earth, are pulled toward it constantly, but because earth has huge mass, velocity and inertia perpendicular to that pull, it orbits.  We the people are attracted much more strongly to the earth than the sun, being closer and share its velocity and "fall" with it in orbit

3) even though earth is a non inertial frame of reference why don't we feel any force when it turns on the circular motion around the sun?

   Any forces we would feel from rotation of earth or orbit around sun are overwhelmed by force of very nearby earth.  In fact, water on the earth is affected by the sun - one high tide a day is due to the bulge of water being pulled toward the sun and the other due to bulge caused by water being flung outward as earth curves away from it and lower force of sun on far side - but tides are only a few feet in 4000 mile radius.

Answer 10

1)It falls because of gravity. Now the question is that why near you.

This is because the ball has zero horizontal velocity relative to the boat. That is why it has zero horizontal displacement relative to the boat. When the ball falls just below the point from where it was dropped, then the ball's horizontal displacement relative to the boat is zero.

If we look relative to the Earth, then the ball does not have zero horizontal velocity. Rather, it has the same horizontal velocity as the boat. That is why it falls just below the point from where it was dropped.

2) By Newton's second law, acceleration should be in the direction of the force. Earth orbits round the Sun. Together with Earth, we are also orbitting towards the Sun. In the frame of reference of the Sun, we are not moving in a straight line. Rather we move in an elliptical path. Because of which our velocity continuously changes. Change in velocity means that we have acceleration. This acceleration is towards the Sun.

3) Let M = Sun's mass

m = mass of a person on the Earth

Gravitational force on the person from the Sun

= F = GMm/d^2

d = distance of the person from the Sun's centre.

LThe acceleration caused due to F = F/m

= GM/d^2

G = 6.67 * 10^-11 Nm^2/kg^2

M = 2*10^30 kg

The distance between the person and the Sun is very close to the Sun-Earth distance. Therefore, to a good approximation

d = distance between Earth and Sun = 1.5*10^11

Therefore the acceleration due to F

= 6.67*10^-11 * 2*10^30/(1.5*10^11)^2 m/s^2

= 6.67*10^-11 * 2*10^30/(1.5^2 * 10^22) m/s^2

= 6.67 * 2 * 10^19/(2.25 * 10^22) m/s^2

= (13.34/2.25) * (10^19/10^22) m/s^2

= 5.93 * 10^-3 m/s^2

This is very small compared to the acceleration due to gravity on Earth = 9.8 m/s^2

That is why the effect because of Earth being non-inertial frame is not noticed by us.

Note: In the above calculation, I have used approximate values because the purpose was not to find the exact effect of Earth being non-inertial frame. But to show the effect is very small.