Superman ferma in 5,0 ∙10^(-3) s un treno inizialmente in corsa alla velocitá di 216km/h. Qual é l’accelerazione media del treno
1 answer:
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Joel does not move because the frictional force acting on him is also 60 N
Explanation:
The force of static friction is a force that acts on objects at rest, in the direction opposite to the force that is trying to put the object in motion.
The value of the force of static friction goes from zero to a maximum value given by
where
is the coefficient of static friction
m is the mass of the object
g is the acceleration of gravity
In order to move the object, the force which is pushing it must overcome this maximujm value of the force of friction, otherwise the force of friction will balance the pushing object preventing the object to move.
In this problem, there are two forces acting on Joel:
- The pushing force, , forward
- The frictional force, , backward
According to Newton's second law of motion,
where a is the acceleration of Joel. However, Joel is at rest, so the acceleration is zero:
which means that the frictional force is equal to the pushing force of 60 N, preventing Joel from moving.
Learn more about force of friction:
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