A massless spring with force constant 536 N/m is fastened at its left end to a vertical
wall, as shown below.
The acceleration of gravity is 9.8 m/s
2
.
6 kg 3 kg
536 N/m
Initially, the 6 kg block and 3 kg block rest
on a horizontal surface with the 6 kg block in
contact with the spring (but not compressingit) and with the 3 kg block in contact with the
6 kg block. The 6 kg block is then moved to
the left, compressing the spring a distance of
0.4 m, and held in place while the 3 kg block
remains at rest as shown below.
6 kg 3 kg
k 0.4 m
Determine the elastic energy U stored in
the compressed spring.
Answer in units of J.