A spring-powered toy rifle propels a 15 g pellet along a horizontal 0.25 m long barrel
PHYSICS · Multi-part · AP · Physics 1: Algebra-based · Work Energy and Power · Work Energy and Power
Problem
A spring-powered toy rifle propels a 15 g pellet along a horizontal 0.25 m long barrel. The spring has a force constant of 800 N m⁻¹ and is initially compressed and then released when the trigger is pulled. Because of internal friction and sound, only 35% of the elastic potential energy stored in the spring is converted into the kinetic energy of the pellet at the muzzle.
(i) The pellet leaves the muzzle with a speed of 12 m s⁻¹. Calculate its kinetic energy at that instant.
(ii) Using the given efficiency, determine the elastic potential energy that must have been stored in the spring before the shot.
(iii) Hence find the compression of the spring required prior to firing.
(iv) If the same spring is compressed by the same amount but the efficiency falls to 25% because of wear, compute the new muzzle speed of the pellet.