A2.00 kg block hangs from a spring balance calibrated in newtons that is attached to the ceiling of an elevator.(a) what does the balance read when the elevator is ascending with a constant speed of 29 m/s? ? n(b) what does the balance read when the elevator is descending with a constant speed of 25 m/s? ? n(c) what does the balance read when the elevator is ascending at 39 m/s and gaining speed at a rate of 10 m/s2? ? n(d) suppose that from t = 0 to t = 4.9 s, the elevator ascends at a constant speed of 10 m/s. its speed is then steadily reduced to zero during the next 3.2 s, so that it is at rest at t = 8.1 s. describe the reading of the scale during the interval 0 < t < 8.1 s. t0 ? 4.9 = nt4.9 ? 8.1 = n

Part a)

Part b)

Part c)

Part d)

from t = 0 to t = 4.9 s

so the reading of the scale will be same as that of weight of the block

Then its speed will reduce to zero in next 3.2 s

from t = 4.9 to t = 8.1 s

The reading of the scale will be less than the actual mass

Explanation:

Part a)

When elevator is ascending with constant speed then we will have

So it will read same as that of the mass

Part b)

When elevator is decending with constant speed then we will have

So it will read same as that of the mass

Part c)

When elevator is ascending with constant speed 39 m/s and acceleration 10 m/s/s then we will have

Reading is given as

Part d)

Here the speed of the elevator is constant initially

from t = 0 to t = 4.9 s

so the reading of the scale will be same as that of weight of the block

Then its speed will reduce to zero in next 3.2 s

from t = 4.9 to t = 8.1 s

The reading of the scale will be less than the actual mass

5 w for 1hr = 5x60x60 joules=300x60=3000x6=18,000j as total energy conversion. efficiency of bulb needed for radiant to thermal within 18000

volts times amps 6 x 0.5 3w