In which situations can you conclude that the object is undergoing a net interaction with one or more other objects? (Select all
that apply. 1)A car travels at constant speed around a circular race track.
2)A book slides across the table and comes to a stop.
3)A hydrogen atom remains at rest in outer space.
4)A proton in a particle accelerator moves faster and faster.
5)A spacecraft travels at a constant speed toward a distant star.
<em>4, A proton in a particle accelerator moves faster and faster.</em>
Explanation:
A particle accelerator according to Wikipedia.com is a machine that uses electromagnetic fields to propel charged particles to very high speeds and energies, and to contain them in well-defined beams. Large accelerators are used for basic research in particle physics.
As the proton moves around, it collides with other proton and the wall of the accelerator thereby undergoing net interaction.
<span>Unless the pig moves static friction acts on it once the pig starts moving kinetic friction comes in to play so when the pig is not moving=frictional force acting on it =normal force*co-efficient of static friction.</span>
