A ball moves at constant speed. Can I then safely say that the result of the forces acting on the ball is zero? I need good explanation on this one
Answers
#BAL
According to the second law of motion, a force F applied to an object with mass M inevitably produces an acceleration of F/M. If there is no force applied to an object or if the forces applied to it balance each other, the net acceleration will be zero. The object will either be in rest or travel in a uniform straight line at constant velocity.
The converse is also true. An object at a constant velocity is not subject to any forces or the forces which it is subject to balance each other.
However we cannot tell the same thing about speed, as it is not a vector. The earth, while it rotates around the sun does so at constant speed while experiencing a constant centripetal acceleration. The velocity, however, is not constant because we can observe that the direction of motion changes every moment, approximating the locus into a circle.
The boat you mention will continue in its straight path at CONSTANT velocity due to its inertia, as long as the force due to the engine EXACTLY overcomes the friction. If this force exceeds the frictional force, the boat will accelerate. If it is less than the friction, the boat will decelerate and eventually stop. So,
An object moving with a constant velocity implies the net forces being zero.
BUT,
A constant speed does not guarantee the same, for instance in circular motion