A block of mass 2 kg is attached to one end of a massless spring whose other end is fixed at a wall. The spring-mass system moves on a frictionless horizontal table. The spring's natural length is 2 m and spring constant is 200 N/m. The block is pushed such that the length of the spring becomes 1 m and then released. At distance x m (x < 2) from the wall, the speed of the block will be
- 10 [1 - (2 - x)2 ] 12 m/s
- 10 [1 - (2 - x)2 ] 32 m/s
- 10 [1 - (2 - x)2 ] m/s
- 10 [1 - (2 - x)2 ]2 m/s
Answer
(1) 10 [1 - (2 - x)2 ] 12 m/s
Solution
Angular frequency: = km = 2002 = 10 rad/s
The block is released from rest with compression 2 - 1 = 1 m amplitude A = 1 m (about the natural-length position).
At distance x from the wall, displacement from the mean position = 2 - x.
Speed in SHM: v = A2 - y2
v = 10 1 - (2 - x)2
= 10 [1 - (2 - x)2 ] 12 m/s
Answer: (1)