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2. According to Newton's second law, F = ma F = m a. If acceleration is zero then the force must be zero, but assuming you have an object moving with a constant velocity of say 2ms−1 2 m s − 1, and that object strikes you, then obviously some sort of 'force' would be felt by you, so my question is what do you call that 'force' since it ...
If a body is moving with constant velocity, acceleration is zero. So net force acting on it will be also zero. But the body has energy due to its constant motion. Take the case of a freely falling body: it reaches its terminal velocity (120mph) when gravity = air resistance (drag). So it doesn't have net forces acting on it.
The same goes for acceleration. If this is not the case in a certain situation and the difference between "constant velocity" and "constant speed" is important, you can expect the meaning to be clear from the context, or stated explicitly. As for your third sentence, a constant magnitude of velocity does not mean there is no acceleration.
Even though the speed is constant in this particular example, the direction changes all the time. The velocity of an object changes when the net force acting on it is not zero. When the net force is perpendicular to the velocity, it does no work and the kinetic energy of the object remains constant, so the force only changes the direction of ...
so that an instantaneous acceleration increases the velocity to some constant value. )) now lets say velocity is 1 m/s. lets calculate Work done by "Friction" in 2 sec ( only by friction ) distance travelled = 1 x 2 = 2 m. Friction Force is opposite to displacement vector , so ,
The average velocity of a particle during some elapsed time $\Delta t$ is, in words, the constant velocity that gives the same displacement in the same elapsed time. Mathematically, the average velocity is given by $$\mathbf{v}_{avg} = \frac{\Delta \mathbf{r}}{\Delta t}$$
Examples are pushing an object at constant velocity on a surface with friction and lifting an object at constant velocity. In the first example the person pushing the object does positive work on the object and the kinetic friction force does an equal amount of negative work on the object.
Power(P)=Force(F) . Velocity(V) "In the straightforward cases where a constant force moves an object at constant velocity, the power is just P = Fv. In a more general case where the velocity is not in the same direction as the force, then the scalar product of force and velocity must be used." Source-Hyperphysics
Rain drop falls with a constant velocity because the weight (which is the force of gravity acting on body) of the drop is balanced by the sum of the buoyant force and force due to friction (or viscosity )of air. Thus the net force on the drop is zero so it falls down with a constant velocity.
It will ALWAYS have constant velocity when the net force (the sum of all the forces acting on an object: in this case pulling and frictional forces response) is zero. This is the statement of Newton's 1st law of motion.