A mass only travels in a circle while something keeps pulling it inward. This diagram shows that real, inward centripetal force — and the outward centrifugal feeling it produces, which is not a real force at all.
A ball on a string, a car on a bend, a moon around a planet — all are moving in circles, and speed alone never does that. Velocity is a direction as well as a speed, so anything following a curve is changing direction from one instant to the next. Any change in velocity is an acceleration, and an acceleration always needs a force behind it.
That force is called the centripetal force. It points straight to the centre of the circle and acts on the moving object. Because it is always at right angles to the motion, it never makes the object speed up or slow down — it only steers it, bending a straight path into a circle.
When you are the one turning, you feel pushed outward. That outward sensation is the centrifugal force: an apparent force that appears only in the rotating frame, when you describe motion from inside the turn. From the outside, no separate force pushes outward — the object is simply carrying on and being pulled inward at the same time.
Anything moving in a circle is changing direction every instant, so a force must act on it toward the centre. Without that force the path would be a straight line.
The inward pull is called the centripetal force. It acts along the radius — the line from the mass to the centre — and never along the direction of travel.
The faster the mass moves, or the tighter the circle, the larger the force needed. In symbols, F = m·v² / r: doubling the speed needs four times the force. That is why a car needs far more grip in a fast, tight corner.
Being forced to turn feels like being thrown outward, and we call that sensation centrifugal force. It is apparent only: it exists in the rotating frame, with no outside agent actually pushing the mass outward.
Cut the string and there is no centripetal force left, so the mass simply continues along the tangent in a straight line. It never flies outward from the centre — it flies off at a tangent to the circle.
No — not as a force on the moving object. In a fixed frame the only sideways force on the mass is the inward centripetal force. Centrifugal force is an apparent, outward effect felt in a rotating frame, like the push you feel in a car going round a corner.
Centripetal force is real and points inward, toward the centre, acting on the moving object. Centrifugal force is apparent and points outward; it appears only when you describe the motion from a rotating frame.
Whatever holds the object on its curve: tension in a string, gravity for a moon or a satellite, friction between tyres and road, or the push of a banked track. The name describes the job, not a new kind of force.
Because turning faster changes your direction faster. Doubling the speed needs four times the force, which is why a car requires far more grip in a tight, fast corner.
The object stops turning and flies off along the tangent, in a straight line, just as Newton's first law predicts. A snapped string sends the mass straight ahead, not outward from the centre.