Answer:
None of the statement is false - all of them are true
Explanation:
Let's analyze each statement:
- The net force on the block is zero newtons. --> TRUE. In fact, the block is moving across the surface at constant speed: constant speed means zero acceleration, and according to Newton's second law,
F = ma
this also means a net force of zero newtons.
- The frictional force on the block has magnitude 3.0 N. --> TRUE. The horizontal acceleration of the block is zero, so the resultant of the horizontal forces must be zero:
[tex]F-F_f = 0[/tex]
where F = 3.0 N is the horizontal push and [tex]F_f[/tex] is the frictional force. From the equation, we find
[tex]F_f = F = 3.0 N[/tex]
- The coefficient of kinetic friction between the block and the surface is 0.30. --> TRUE. The frictional force is 3.0 N, and its expression is
[tex]F_f = \mu_k (mg)[/tex]
where [tex]\mu_k[/tex] is the coefficient of kinetic friction and (mg)=10 N is the weight of the block. Solving for [tex]\mu_k[/tex], we find
[tex]\mu_k = \frac{F_f}{mg}=\frac{3 N}{10 N}=0.30[/tex]
- The direction of the total force that the surface exerts on the block is vertically upward. --> TRUE. Since gravity is acting downward, and the block is not accelerating on the vertical direction neither, there must be an equal and opposite force acting upward on the block: and this force is the force exerted by the surface on the block.
- The block is not accelerated. --> TRUE: the block is moving at constant speed, so its acceleration is zero.
