Use Kepler’s second law to convince yourself that Earth mustmove faster in its o

Question

               Use Kepler’s second law to convince yourself that Earth mustmove faster in its orbit during the northern-hemisphere winter,when it is closest to the Sun, than during the Summer, when it isfarthest from the Sun.

               Give an example in which the net force acting on an object is zero,yet the net torque isnonzero.

               Give an example in which the net torque acting on an object iszero, yet the net force isnonzero.

Work-EnergyTheorem

               Is work done in a tug of war? Explain your answerplease.

What will be kinetic energyof an arrow shot from a bow having a potential energy of 40 Joules(in absence of frictionalforces)?

            The driver of a car slams on her brakes to avoid colliding with adeer crossing the highway. What happens to the car’s kineticenergy as it comes torest?

conservation ofangular momentum.

If two objects collide and one isinitially at rest, is it possible for both to be at rest after thecollision? Is it possible for only one to be at rest after thecollision? Explain

Explanation / Answer

it is not possible to calculate the torque acting on an objectwithout first specifying the origin because torque is defined as aforce that acts perpendicular to the origin at a specific lengthfrom it as well. a bar in which two equal force are acting in opposite direction onopposite ends of the bar will result in a zero force and a non-zerotorque a bar in which two equal forces are acting in the same direction onopposite ends of the bar will result in zero torque and non-zeroforce no work is done until one group displaces the other from theirstarting position, so you could say that no work is done until thetug is over. energy will be conserved so all the potential energy of the bowwill be converted to kinetic energy of the arrow so the arrow willhave 40 J of kinetic energy. the car's kinetic energy is converted to thermal energy in thebrake discs and pads as well as thermal energy from the tiressliding along the pavement if the tires lock up. It would only be possible for both items to be at rest after thecollision if an outside force acts on the system during thecollision or if all the energy is converted into sound or thermalenergy during the collision. it is possible for one item tobe at rest after the collision if it is an elastic collision, thisis often witnessed in games of pool.

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