Could be easy for some people and hard for some people.
Answer:
Final speed of striped ball is 3 m/s in left direction .
Explanation:
Given :
Two billiard ball with the same mass moves toward the left at the same speed 3 m/s .
Let , us assume right hand side direction to be positive and left hand side direction to be negative .
Also , let speed of ball after collision is (striped ball ) u and (solid ball) v .
It is also given that the collision is elastic .
Therefore , kinetic energy is conserved .
...... ( 1 )
Also , by conserving linear momentum .
We get :
...... ( 2 )
Putting value of u from equation 2 to equation 1 .
We get :

And , u = -3 m/s .
Therefore , final speed of striped ball is 3 m/s in left direction .
Hence , this is the required solution .
The answer should be B. Fault.
formula= W=f*d
w=work done
f=force
d=distance
w=f*d
w= 5n*0(does not budge)means does not move so distance is zero
w=5J
The work done by the children on the sumo wrestler is 5J
Answer:
a) 9 - 1.2 = 7.8 N
b) Since the force exerted by the box is it's weight, it acts in a downward direction. So the box will exert a force downward (perpendicular to the horizontal surface).
Explanation:
A 9N block would exert 9N of normal force on the horizontal plane under normal conditions. But in this case, we have a spring taking away some of the force by applying an upward force on the box.
So the force exerted by the box on the surface would now be:
a) 9 - 1.2 = 7.8 N
b) Since the force exerted by the box is it's weight, it acts in a downward direction. So the box will exert a force downward (perpendicular to the horizontal surface).