1) C) Ben is right because the electricity from the light is transformed into heat and light.
Explanation:
The Law of Conservation of Energy states that energy cannot be created nor destroyed, but only transformed.
In this particular example, energy is not destroyed. In fact, the electrical energy (produced, for instance, by the battery inside the torchlight) is converted into light (electromagnetic wave) and heat (thermal energy). So, Ben is right, because energy is just transformed into other types of energy.
2) D) Neither is completely right. Shawn is partly correct since kinetic energy depends on mass, but Greg is also partly right since it also depends on speed.
Explanation:
The kinetic energy of an object is given by:
where m is the mass of the object and v its speed. From the formula, we see that neither Shawn nor Greg is completely right, because the kinetic energy depends both on the mass and the speed, and:
- Greg only told about the speed
- Shawn only told about the mass
3) B) Dan's sister was correct because Dan's legs touched the car seats. That is an indicator of heat transfer by conduction.
Explanation:
Conduction is the method of heat transfer that occurs between two solid objects, when they are in contact with each other, and it is due to the collisions between the molecules of the two objects: when colliding, the molecules of the hotter object transfer part of their kinetic energy to the molecules of the colder object.
In this case, Dan legs are in contact with the car seat (which is at higher temperature), so heat is transferred from the seat to Dan legs by conduction.
