A 1.0-kg weight is suspended from the middle of a 1.3-m long rope that has one end fixed to a wall. What force would you have to exert on the other end of the rope to pull it perfectly horizontal?

a. 49 N

b. 0.98N

c. 980N

d. 0.49N

e. It cannot be done

e. It cannot be done

Explanation:

Let T be tension in the rope. The component of T in vertical direction will balance the weight.

Since T makes angle 90 degree with vertical (since rope is perfectly horizontal)

2T cos 90 = mg

T = mg / 2 cos 90

= mg / 2 x 0

= infinity

Tension will have to be infinity which is not possible.