Question

A spring of spring constant 5 × 10³ N/m is stretched initially by 5cm from the unstretched position. Then the work required to stretch it further by another 5 cm is

• A. 6.25 N-m
• B. 12.50 N-m
• C. 18.75 N-m
• D. 25.00 N-m

Answer 1

Answer: (C)

18.75 N-m

Answer 2

$W = \frac { 1 } { 2 } k \left( x _ { 2 } ^ { 2 } - x _ { 1 } ^ { 2 } \right) = \frac { 1 } { 2 } \times 5 \times 10 ^ { 3 } \left( 10 ^ { 2 } - 5 ^ { 2 } \right) \times 10 ^ { - 4 }$ $= 18.75 \mathrm {~J}$