I think that it is false. You cannot exert force directly on an object without the object exerting a force on you. Newton has a law that states that for every action there is a reaction.This means that if you exert a force on an object it will do same but in the opposite direction of your force.
Answer:
Total momentum before and after the collision = 76800 kgm/s along north.
Explanation:
Let positive x axis represent east and positive y axis represent north.
Momentum is conserved, that is total momentum before and after the collision are same.
A 1200 kg car traveling north at 14 m/s is rear-ended by a 2000 kg truck traveling at 30 m/s.
That is 1200 kg is moving north at 14 m/s and 2000 kg truck is also moving north at 30 m/s.
Momentum of car = 1200 x 14 j = 16800 j kgm/s
Momentum of truck = 2000 x 30 j = 60000 j kgm/s
Total initial momentum = 16800j + 60000j = 76800 j kgm/s
Total momentum before and after the collision = 76800 kgm/s along north.
Explanation:
Problem 2.5, mixing dough.
Please note dimensional units and standard formulas for energies.
Input:
Electrical energy = VIT = 110 V * 1.5 A * 5 min. * 60 s/min = 49500 joules = 49.5 kJ
Output:
Warming of dough = mCΔT = 1 kg * 4.2 kJ/(kg*K) * 5 deg.K = 21 kJ
Dissipation of energy = remainder of input energy = (49.5-21) kJ = 28.5 kJ
Fraction of energy converted to energy of dough = 21 kJ / 49.5 kJ
= forty-two percent (to the nearest percent)
The last item, dissipation of energy could be attributed to:
1. Loss in efficiency of mixer in the form of mechanical friction, heating up due to resistance of motor circuit, etc.
2. Loss in mechanical mixing of dough due to friction between mixer paddle and dough in the form of heat, part of which stays with dough (thus heating up of dough), and the remainder heats up the dough container, loss of heat to environment, air, heat of vaporization of water content of dough, etc.
A unit for measuring frequency, equal to one cycle per second. If a sound wave has a frequency of 20,000 Hz, this means that 20,000 waves are passing through a given point during the interval of one second.