Answer:
a)Work done by fireman= 2.15 Btu
b) Time t= 0.86 sec
Explanation:
Given that
Weight = 280 lbf
We know that 1 lbf = 4.44 N
so 280 lbf = 1245.5 N
Weight =1245.5 N
Height h = 60 ft
We know that
1 ft = 0.3048 m
So 60 ft = 18.28 m
h =18.28 m
Power = 3.5 hp
We know that
1 hp =0.74 KW
So 3.5 hp = 2.61 KW
Power = 2.61 KJ/s
So the work done by fireman = Weight x h
Now by putting the values
Work done by fireman= 1245.5 x 18.28 J
Work done by fireman= 2267.74 J
Work done by fireman= 2.26774 KJ
We know that 1 Btu= 1.05 KJ
So 2.266 KJ = 2.15 Btu
Work done by fireman= 2.15 Btu
We know that ,rate of work is called power.
Power x time = work
2.61 x t = 2.26
So t= 0.86 sec
D. Is repelled by a magnet
Answer:
d = 175 miles
Explanation:
Train is moving towards East with constant speed of 50 mph
While car is moving at speed of 30 mph
so after t = 3 hours
the distance moved by the train is given as


at the same time the distance moved by the car is given as

now we know that both car and train is moving perpendicular to each other
So the distance between them after t = 3 hours is given as



The answer is D, the amount of energy stays the same.
Answer:
Clouds form when below the dew point