- .An object of mass 3 kg is attached to a spring of spring constant 50 N/m. How far is the
equilibrium position of this spring system from the point where the spring exerts no force on the
object?
(A)0.15 m
(B)0.3 m
(C)0.5 m
(D)0.6 m
(E)1.5 m
Que st io ns 8 –1 0 ref er t o a p en d ul um i n it s up ward swi ng. Th at i s, t he ve l oci ty ve cto r for
t he p en d ul um i s p o in ti ng i n th e d ire ct io n of E.- .What is the direction of the force of gravity on the pendulum bob?
(A)A
(B)B
(C)C
(D)D
(E)E - .What is the direction of the net force acting on the pendulum?
(A)A
(B)B
(C)C
(D)D
(E)E - .If the pendulum string is suddenly cut, what is the direction of the velocity vector of the pendulum
bob the moment it is released?
(A)A
(B)B
(C)C
(D)D
(E)E
Explanations
- A
If the pulley system doesn’t move, then the net force on both masses is zero. For mass m, that means that
the force of gravity, mg, pulling it downward, is equal to the force of tension in the rope, pulling it upward. If
the force of tension pulling mass m upward is mg, then the force of tension pulling mass M toward the edge