Answer:
0.0044 J
Explanation:
The kinetic energy of an object is given by:
[tex]K=\frac{1}{2}mv^2[/tex]
where
m is the mass of the object
v is the speed
For the ball in this problem,
m = 50.0 g = 0.050 kg
v = 42 cm/s = 0.42 m/s
Therefore, the kinetic energy is
[tex]K=\frac{1}{2}(0.050 kg)(0.42 m/s)^2=0.0044 J[/tex]