A particle moves along a straight path through a displacement d = 2.5i + cj while a force F = 8.5i + -8.5j acts on it. The displ
acement is measured in meters and the force is measured in Newtons. (Other forces also act on the particle.) What is the value of c if the work done by F on the particle is zero?
Assuming no external forces acting during the collision, total momentum must be conserved, as follows:
The initial momentum p₀, can be written as follows:
The final momentum pf, can be written as follows:
Since (2) and (3) are equal each other, we can solve for the only unknown that remains, v₂₀, as follows:
This means that the 2.0-kg object was moving at 23 m/s in a direction opposite to the 6.0-kg object, so its initial speed, before the collision, was 23.0 m/s.
