Question

An object is acted upon by the forces f1=4i n and f2 = (i - j) n. if the displacement of the object is ( i + 6j - 6k ) metre, the change in kinetic energy of the object is

Answer 1

Answer: The change in kinetic energy of the object is -1 J.

Explanation:

Given that,

$f_{1} = 4i n$

$f_{2} = (i-j) n$

Displacement $d = (i+6j-6k)$

Now, the resultant force

$F = f_{1}+f_{2}$

$F = 4i+i-j$

$F = 5i-j$

According to work energy theorem

$\Delta k= W$

The work done is

$W = f\cdot d$

$W = (5i-j)\cdot (i+6j-6k)$

$W = 5-6+0$

$W = -1 J$

Hence, the change in kinetic energy of the object is -1 J.