a moving object collides with an object initially at rest. is it possible for both objects to be at rest after the collision?
can one of them be at rest after the collision? is it possible to have a collision in which all kinetic energy is lost? explain each answer and if yes to any of them, give an example
question one: no, because kinetic energy transfers after contact
question two: yes, because if an object is motionless, then a moving object transfers all its kinetic energy to the motionless object, then the previously moving object would stop and force the other previously motionless object to continue in its place.
for example, when a penny hits another penny at the bottom of a stack of pennies, the lower penny continues in place of the penny now at the bottom of the stack.
question three: no for the same reason as question one.
I think it the problem is momentum conservation, not KE conservation. KE can be conserved by not transfering motion, but heat.
You are correct that the conservation of momentum is the key factor in determining whether both objects can be at rest after a collision. When two objects collide, the total momentum before the collision is equal to the total momentum after the collision, assuming no external forces are involved. This principle is known as the conservation of momentum.
1. Is it possible for both objects to be at rest after the collision?
No, it is not possible for both objects to be at rest after the collision. According to the conservation of momentum, if an object is in motion and collides with another object initially at rest, the total momentum of the system cannot be zero after the collision. At least one of the objects must be in motion to conserve momentum. Therefore, after the collision, one object will continue to move while the other one may be at rest or in motion.
2. Can one of them be at rest after the collision?
Yes, it is possible for one object to be at rest after the collision. In an elastic collision, where kinetic energy is conserved, the moving object can transfer all its kinetic energy to the stationary object. As a result, the initially stationary object will start moving, while the moving object will come to rest. This situation occurs when the masses of the objects are significantly different.
For example, consider a cart moving with high velocity colliding with a stationary wall. After the collision, the wall remains stationary, while the cart comes to a complete stop, transferring its kinetic energy to the wall.
3. Is it possible to have a collision in which all kinetic energy is lost?
No, it is not possible to have a collision where all kinetic energy is lost. In an ideal elastic collision, both momentum and kinetic energy are conserved. However, in an inelastic collision, kinetic energy is not conserved, but is transferred to other forms of energy such as heat, sound, or deformation.
For example, when two clay balls collide, they may stick together and deform, losing some of their initial kinetic energy in the process.
In summary, the conservation of momentum determines whether both objects can be at rest after a collision. Only when the object masses are significantly different can one object come to rest while transferring its kinetic energy to the initially stationary object. In any collision, whether elastic or inelastic, the total kinetic energy is never completely lost but is transformed into other forms of energy.