A student wants to find out the speed of a high-speed projectile, but doesn't have a high-speed measuring device. However, the student realizes that this problem can be solved using conservation of linear momentum and one-dimensional kinematics. The studen glues a long strip of sand paper with coefficient of friction of 0.200 next to a 5.00 kg block of wood on a otherwise frictionless table. The 0.150 kg projectile is fired horizontally at the bloc and embeds itself in the block. After the collision, the block moves instantly from the frictionless table onto the sand paper and comes to a stop 0.500m further. The student realizes taht 1-D kinematics and Newton's 2nd law can be used to figure out the speed of the combined projectile/block just after the collsion. Knowing the speed of the combined projectile/block just after the collision, the student can then use conservation of linear momentum to find the speed of the projectile just before the collision.
a) what is the speed of the combined projectile/block just after the collision?
b) what is the speed of the projectile just before the collision?