Four radioactive 10-gram (g) samples with their remaining isotope mass are listed in the table that spans 50 years. Which isotope would be expected to have the longest half-life?
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A.
Silver-108

B.
Mercury-194

C.
Californium-249

D.
Americium-241

10 years 9.84 g 9.80 g 9.84 g 9.85 g
20 years 9.68 g 9.61 g 9.67 g 9.69 g
30 years 9.53 g 9.42 g 9.51 g 9.54 g
40 years 9.38 g 9.24 g 9.36 g 9.39 g
50 years 9.23 g 9.06 g 9.20 g 9.25 g

Abody of weight 60 kg is standing in a lift the lift going upward with a uniform velocity of 4.9 metre per second slows down and stops in two seconds then apparent weight of the body during the slow down process is

With i really need the correct answer!

For problems 1-3, consider a simple dc brush motor with a permanent magnet stator. with an an consider a simple dc brush motor with a permanent magnet ae supply voltage of 100 v, the no-load speed of the motor is 1000 rpm. this motor can provide a torque of 1.9 n-m at 800 rpm drawing a current of 2 a current are both zero at no load.) 1. with an armature supply voltage of 100 v, the motor is operated at 900 rpm. what is the motor torque? what is the mechanical power delivered by the motor? what is the current draw? what is the electrical power input? what is the energy efficiency of the motor? with an armature supply voltage of 100 v, the motor is operated at 1100 rpm (where it acts as a generator). what torque input is required? what mechanical power is required what current is generated? what is the electrical power generated? what is the energy efficiency of the motor acting as a generator? 2. with an armature supply voltage raised to 120 v, the motor is operated at 1000 rpm. what is the no-load speed? what is the motor torque? what is the mechanical power delivered by the motor? what is the current draw? what is the electrical power input what is the energy efficiency of the motor? 3.