To identify which force is represented by -7 N, let's analyze the nature of the forces involved when pushing a box across a table.
1. Push Force:
- The push force is applied by the person pushing the box. It is directed in the direction of the intended motion. It should be a positive value reflecting the direction the person is pushing.
2. Normal Force:
- The normal force is the perpendicular contact force exerted by a surface on an object resting on it. On a flat horizontal table, this force is directed upwards and balances the weight of the object. It is positive and equal in magnitude to the downward force of gravity.
3. Force of Gravity:
- The force of gravity acts downward on the box and is the product of the mass of the box and gravitational acceleration (9.8 m/s²). It is also a positive value.
4. Force of Friction:
- The force of friction opposes the motion of the box. It is directed opposite to the direction of the push force. If the box is pushed to the right, the force of friction will act to the left. This force is typically negative as it resists the motion.
Given the measured forces:
- [tex]\(10 N, 14 N, -7 N, -10 N\)[/tex]
Positive forces (10 N and 14 N) are likely associated with the push force and possibly the normal force or force of gravity. The negative forces (-7 N and -10 N) are likely directions opposing the motion, associated with the friction force.
In this particular case:
- -7 N is the force acting in the opposite direction of the motion.
Thus, the force represented by -7 N is the force of friction.
