NIMCET 2013 — Mathematics PYQ
NIMCET | Mathematics | 2013Forces 3i^+2j^+5k^ and 2i^+j^−3k^ are acting on a particle and displace it from the point 2i^−j^−3k^ to the point 4i^−3j^+7k^. The work done by the force is:
Choose the correct answer:
- A.
18 units.
- B.
30 units.
- C.
24 units.
(Correct Answer) - D.
36 units.
24 units.
Explanation
Solution
1. Calculate the Resultant Force (F):
F=F1+F2
F=(3i^+2j^+5k^)+(2i^+j^−3k^)
F=(3+2)i^+(2+1)j^+(5−3)k^
F=5i^+3j^+2k^
2. Calculate the Displacement Vector (d):
Let the initial position be r1=2i^−j^−3k^ and the final position be r2=4i^−3j^+7k^.
d=r2−r1
d=(4i^−3j^+7k^)−(2i^−j^−3k^)
d=(4−2)i^+(−3+1)j^+(7+3)k^
d=2i^−2j^+10k^
3. Calculate Work Done (W):
W=F⋅d
W=(5i^+3j^+2k^)⋅(2i^−2j^+10k^)
W=(5×2)+(3×−2)+(2×10)
W=10−6+20
W=4+20
W=24 units
Explanation
Solution
1. Calculate the Resultant Force (F):
F=F1+F2
F=(3i^+2j^+5k^)+(2i^+j^−3k^)
F=(3+2)i^+(2+1)j^+(5−3)k^
F=5i^+3j^+2k^
2. Calculate the Displacement Vector (d):
Let the initial position be r1=2i^−j^−3k^ and the final position be r2=4i^−3j^+7k^.
d=r2−r1
d=(4i^−3j^+7k^)−(2i^−j^−3k^)
d=(4−2)i^+(−3+1)j^+(7+3)k^
d=2i^−2j^+10k^
3. Calculate Work Done (W):
W=F⋅d
W=(5i^+3j^+2k^)⋅(2i^−2j^+10k^)
W=(5×2)+(3×−2)+(2×10)
W=10−6+20
W=4+20
W=24 units
