Gravitational force
Drop anything — a pencil, a ball, a leaf — and it always falls the same way: straight down towards the ground. Throw something upward and it always slows, pauses for an instant, and falls back. Behind both of these everyday observations is a single, constant pull: gravitational force, the force with which the Earth attracts every object towards itself. This chapter, from the CBSE Class 8 unit "Exploring Forces," keeps gravitational force strictly qualitative. There is no formula, no numerical gravitation problem, and no talk of acceleration here — those wait for higher grades. What matters now is the idea: gravitational force is a non-contact force, it acts across empty space, and — unlike magnetic or electrostatic force — it is always attractive, never repulsive. That one property explains why things fall, why thrown objects return, and why the Moon stays put in the sky instead of drifting off.
Gravitational force is the Earth's constant, non-contact, always-attractive pull on every object towards itself, and it alone explains why dropped things fall and thrown things come back.
The core idea
Gravitational force is the force with which the Earth attracts every object towards itself. Three features define it at this level. It is a non-contact force. The Earth does not need to touch an object to pull on it — the pull acts across the empty space between the Earth and a bird flying high above, or between the Earth and the Moon nearly 400,000 km away. This puts it in the same family as magnetic force and electrostatic force, both of which also act without touching, and sets it apart from contact forces like the muscular force of a push or the frictional force of a sliding surface. It is always attractive. This is the single most exam-relevant feature of gravitational force as studied in this chapter. Magnetic force can attract or repel depending on which poles face each other; electrostatic force can attract or repel depending on the charges involved. Gravitational force has no such switch — the Earth only ever pulls objects towards itself, never pushes them away. There is no orientation, distance, or condition within this syllabus at which gravitational force becomes repulsive. It acts on everything, near or far. Objects resting on the ground, a ball tossed into the air, a satellite in orbit, the Moon itself — all are pulled by the same Earth's gravitational force. The strength of that pull is not part of this syllabus (that needs the formula , studied later); what matters here is only that the pull exists and is always directed towards the Earth's centre.
Why it works
Gravitational force explains three everyday observations that would otherwise seem unconnected, once you accept that the Earth constantly pulls everything towards itself.
Dropped objects fall straight down. The instant an object is released, nothing holds it up any longer, and gravitational force — which never stops acting — pulls it directly towards the Earth's centre. Because the pull is always in the same downward direction, the object always falls the same way, whether it is a pencil, a ball, or a leaf.
Thrown objects slow, pause, and return. When an object is thrown straight up, it leaves the hand moving against the direction of gravitational force. That force keeps acting on the object throughout its flight — during the entire time it never switches off or reverses — so it continuously works against the upward motion, gradually slowing the object down. At the highest point the object is momentarily at rest, but gravitational force is still pulling on it even then, which is exactly why it does not stay floating there: it immediately begins to fall back, speeding up as it descends.
Distant objects like the Moon stay bound to the Earth rather than drifting off. Gravitational force is not limited to objects touching or near the ground; it also acts across large distances, on a bird in the sky or the Moon in orbit. This is the same reasoning that rules out the idea of gravitational force ever becoming repulsive — since it is always attractive, there is no point at which the Earth's pull on a distant object could flip and push it away. Taken together, these three points cover essentially every observation this chapter asks a student to explain: gravitational force is a single, constant, always-attractive, non-contact pull, and every falling or returning object is evidence of it.
Worked example
Question. A student throws a ball straight up into the air and it lands back in the same hand a few seconds later. Explain, stage by stage, how gravitational force acts on the ball throughout this journey, and use the same reasoning to say what would be wrong about claiming the ball "escapes" gravitational force at its highest point.
Step 1. At the moment the ball leaves the student's hand, it is moving upward, but gravitational force begins acting on it immediately — it does not wait for the ball to slow down first. This force is directed downward throughout, opposing the ball's upward motion from the very start.
Step 2. As the ball keeps rising, gravitational force continues to act on it every instant, gradually reducing its upward speed. The ball does not suddenly stop; it is slowed down bit by bit by the same constant pull that will later bring it back down.
Step 3. At the highest point, the ball is momentarily at rest — this is the instant a student might wrongly think gravitational force has "let go" of the ball. In fact gravitational force is still fully acting on it at this exact moment; it is precisely because the pull never stops that the ball cannot remain suspended there.
Step 4. Because gravitational force keeps pulling downward even at that momentary pause, the ball begins to fall, and its speed increases as it descends, all the way until it lands back in the student's hand.
Answer: Gravitational force acts on the ball continuously — while rising, at the highest point, and while falling — so the claim that the ball "escapes" gravitational force at its highest point is wrong; the force never switches off, and that is exactly why the ball returns.
Common traps
- Thinking gravitational force can sometimes push objects away — within this chapter's scope it is always attractive, unlike magnetic or electrostatic force, which can do either.
- Assuming gravitational force disappears once a thrown object reaches its highest point — it is still fully acting during that momentary pause, which is exactly why the object then falls back down.
- Confusing gravitational force with weight, mass, or air resistance — gravitational force is specifically the Earth's pull on an object, a related but separate idea from an object's weight.
- Believing gravitational force only acts on objects very close to the ground — it also acts on objects far above the Earth's surface, such as the Moon.
Ask the tutor: Want to see how gravitational force connects to an object's weight, with worked numbers? Ask the tutor to walk you through that link.
If gravitational force is always attractive, why doesn't everything on Earth just get pulled together into one lump?
Within this chapter's scope, gravitational force does pull every object towards the Earth — which is exactly why things stay on the ground instead of floating off. Objects are not pulled into "one lump" with each other because the Earth's own gravitational pull on them is vastly stronger than any pull between smaller nearby objects, and normal forces from the ground, floor, or table balance that pull so things stay put rather than sinking through the Earth. The detailed comparison of how strong different gravitational pulls are needs the formula studied in later grades, so at this level it is enough to know the pull always exists and is always attractive.
Does gravitational force stop acting on a satellite or the Moon since they don't fall to the ground?
No — gravitational force keeps acting on the Moon and on satellites at every instant, exactly as it does on a dropped pencil. Within this chapter's scope, the key point is simply that the Earth's gravitational force is always attractive and always acting on them, which is what keeps them moving around the Earth rather than drifting away in a straight line. Explaining precisely why a constant pull results in a curved orbit instead of a fall to the ground needs ideas beyond this chapter, but the pull itself never switches off.
Is gravitational force the same thing as weight?
They are closely related but not identical, and this chapter deliberately keeps them separate. Gravitational force is the pull the Earth exerts on an object, and it is this same pull that gives the object its weight — so weight is really the effect of gravitational force acting on an object's mass. In this chapter, focus on gravitational force itself: that it is non-contact, always attractive, and responsible for falling and returning objects. The precise relationship between gravitational force, mass, and weight is explored further in a companion article once you are ready to connect them formally.