Answer:
Final momentum after a head on collision is -2kgm/s
Explanation:
One ball moves to the right and the other moves opposite and momentum is a vector quantity so that considering the direction
Initial momenta are P₁=2x3=6kgm/s P₂=4x(-2)=-8kgm/s
Final momentum is the vector sum of P(final)= 6-8= -2 kgm/s
Answer:
Object should be placed at a distance, u = 7.8 cm
Given:
focal length of convex lens, F = 16.5 cm
magnification, m = 1.90
Solution:
Magnification of lens, m = -
where
u = object distance
v = image distance
Now,
1.90 = 
v = - 1.90u
To calculate the object distance, u by lens maker formula given by:
u = 7.8 cm
Object should be placed at a distance of 7.8 cm on the axis of the lens to get virtual and enlarged image.
Distance, since distance represents how far something has travelled, which would be in our case 2.5m.