Two 110 kg bumper cars are moving toward each other in opposite directions. Car A is moving at 8 m/s and Car Z at –10 m/s when t
hey collide head–on. If the resulting velocity of Car A after the collision is –10 m/s, what is the velocity of Car Z after the collision? –10 m/s –8 m/s 8 m/s 10 m/s
If the maximum static frictional force is 90 N, this means that any applied force that will overcome this force, will cause the piano to slide, so kinetic frictional force applies.
Under these conditions, the net force in the horizontal direction is just the difference between the applied force (which is larger that the static friction force) and the kinetic frictional force, as follows:
By the same token, according Newton's 2nd Law, this force is just equal to the product of the mass of the piano, times the acceleration, as follows:
Scalar quantities have a size or magnitude only and need no other information to specify them. Thus, 10 cm, 50 sec, 7 litres and 3 kg are all examples of scalar quantities.