To analyze the situation of the crate being pushed across the floor, let's break it down step by step:
1. What is the acceleration of the crate?
Since the crate is being pushed at a constant speed, its acceleration is zero.
Acceleration (a) = 0 m/s²
2. How big is the force of friction that acts on the crate?
When an object moves at a constant speed, the net force acting on it is zero according to Newton's first law (the law of inertia). This means that the applied force must be equal in magnitude and opposite in direction to the force of friction.
- Applied Force (F_applied) = 75 N
- Force of Friction (F_friction) = F_applied = 75 N
So, the force of friction acting on the crate is 75 N.
3. Into what forms of energy is the work done on the crate being converted?
When the man pushes the crate and does work on it, this work is converted into various forms of energy.
-
Kinetic Energy: Since the crate moves at a constant speed, its kinetic energy remains constant, though work is done on it to maintain this speed against friction.
-
Thermal Energy: The work done against the force of friction generates heat due to friction between the crate and the floor. The majority of the energy is converted into thermal energy (heat), which raises the temperature of the surfaces in contact.
-
Potential Energy: If the crate is moved vertically (not mentioned but for completeness), some energy might also increase its gravitational potential energy depending on vertical displacement.
In this scenario, the primary conversion is from mechanical work (push) into thermal energy due to friction, while the kinetic energy of the crate remains constant since it is moving at constant speed.
Therefore:
- The work done is primarily converted into thermal energy due to friction.