Question

If the error in measurement of momentum of a particle is 10% and mass is known exactly, the permissible error in determination of kinetic energy is ?

A. 20%
B. 21%
C. 5%
D. 10%

Answer 1

We know,
 K= 1/2 × MV²

We know that 1/2 & M are constants and the only variable thing here is its velocity
So the error only depends on velocity

Using the equation
ΔK / K =ΔV / V + 1
so that,
∴ ( 2 × 10 ) + 1
  = 21 %

Answer 2

If the error in measurement of momentum of a particle is 10% and mass is known exactly, the permissible error in determination of kinetic energy is 21%
Using the equation
ΔK / K =ΔV / V + 1
so that,
∴ ( 2 × 10 ) + 1
  = 21 %