Exercise 6.2
Two players R and S are participating in an arm-wrestling match (Fig. ). At the instant, when the arms tilt to the front direction (out of the page towards you), are the forces exerted by the players balanced? If not, which player exerted the larger force? It is due to the force of friction arising between the Ready to Go Beyond For an object being pushed, apart from the applied force and the force of friction, some other forces may also be acting on it (Fig. ). One of these is the gravitational force (weight) and the other is the force exerted by the surface on which it is placed called the normal force. The weight acts in the downwards direction, whereas the normal force acts in the upward direction perpendicular to the surface. However, the two forces are balanced. Air around the object also exerts a force of friction on the box when the box moves through the air, but in many cases its magnitude is so small that it can be neglected. For the situation shown in Fig. , once the box starts moving and you
Not cross-checked
NCERT prints no numerical answer for this exercise, so this working has not been cross-checked against the book.
NCERT’s answer
No; S
No, the forces are not balanced — player S exerted the larger force.
If the two players pushed with equal and opposite forces, the net force on the joined arms would be zero and the arms would stay put.
The arms do move, so a non-zero net force acts on them.
When two opposite forces are unequal, the net force equals the difference of their magnitudes and points along the larger force.
The arms tilt out of the page towards you, so the larger force is the one pushing in that direction — in Fig. $\displaystyle 6.9$ that is S.