Answer:
475 Joules
Step-by-step explanation:
Kinetic energy in Joules is given by the equation
KE = (1/2) m x v²
where
m = mass of the object in kg
v = velocity in m/s
If velocity is reduced by half from v to v/2, then KE is reduced by 1/4 since
new KE = (1/2) x m x (v/2)² = 1/4 x previous KE
Since previous KE = 1.9 x 10³ J
new KE = 1/4 x 1.9 x 10³ J
= 0.475 x 10³ J = 475 Joules