Can someone help me answer this SHM problem?
A block of mass m, rests on a frictionless horizontal surface. One end of a spring is connected to the block and the other end of the spring is connected to the wall. If the mass is displaced a distance x, it oscillates back and forth at a consistent frequency.
PE=1/2kx^2
If the block is displaced twice as much, what happens to the
A. energy of the system?
B. maximum velocity of the oscillating mass?
C. acceleration of the mass?
A block of mass m, rests on a frictionless horizontal surface. One end of a spring is connected to the block and the other end of the spring is connected to the wall. If the mass is displaced a distance x, it oscillates back and forth at a consistent frequency.
PE=1/2kx^2
If the block is displaced twice as much, what happens to the
A. energy of the system?
B. maximum velocity of the oscillating mass?
C. acceleration of the mass?
1 Answer
See below
Explanation:
The energy equation for this is:
-
#E = T + U# , where: -
#{(T = "kinetic energy" = 1/2 mv^2),(U = "potential (spring) energy" = 1/2 k x^2 ),(E = "total energy of the block" = 1/2 mv^2 + 1/2 k x^2):}# , -
...in each case, at time
#t# .
At maximum extension,
#v = 0, qquad E = U_("max") = 1/2 kx_("max")^2#
At zero extension, the equilibrium position:
#x = 0, qquad E = T_("max") = 1/2 mv_("max")^2#
Finally, using energy conservation again:
#E = 1/2 kx_("max")^2 = 1/2 mv_("max")^2 = " const"#
Now ANSWERING the questions:
A. energy of the system?
Because
Energy will quadruple.
B. maximum velocity of the oscillating mass?
Max velocity will double
C. acceleration of the mass?
For the spring:
#F = - kx#
From Newton's 2nd Law, for the mass:
#bbF = mbba qquad = - kbbx#
Acceleration through the equilibrium will still be zero, but the magnitude of acceleration at the extremities of the motion, when the mass is changing direction, will double