There is no displacement. The frog is back where it began.
Answer:
(A) 3,449,600 N/m
(B) 62,720 poeple
Explanation:
extension of the sling shot (e) = 4 m
mass of projectile (m) = 440 g = 0.44 kg
speed of projectile (v) = 11.2 km/s = 11,200 m/s
average force a person can exert = 220 N
spring constant (k) = ?
(A) When all the elastic potential energy is converted to kinetic energy

rearranging the above equation
spring constant (K) = 
spring constant (K) = 
spring constant (K) = 
spring constant (K) = 3,449,600 N/m
(B) force required to stretch the slingshot (F) = ke = 3,449,600 x 4 = 13,798,400 N
number of people required = required force / average force per person = 13,798,400 / 220 =62,720 poeple
A plane mirror always forms a virtual image. the image and the object are the same distance from a flat mirror, the image size is the same as the object, and the image is upright!
The answer is 36 kilometers per hour, or 10 meters per second.