If a wire 30 cm long is extended to 30.5 cm by a force of 300 N. find the strain energy of wire
0.75 J
7.50 J
75.00 J
750.00 J
Correct answer is A
Energy stored in a stretched wire (strain energy)
= average force x extension
= (1)/2 Fe
= (1)/2 x 300 N (30.5 - 30.0) x 10-2 m
= (300)/2 x 0.5 x 10-2 = 0.75J
55.6 %
50.0%
33.3%
22.2%
Correct answer is C
Efficiency = (MA)/V.R x 100% = (load)/Effort x (1)/V.R
= (800)/400 x (1)/6 x 100% = 33.3%
The surfaces of conveyor belts are made rough so as to?
protect them while carrying loads
prevent the loads from slipping
enable them to carry more load
make them stronger
Correct answer is B
Rough surface promotes friction. Therefore, roughness of conveyor belt prevents the load from slipping
2 ms-2
5 ms-2
20 ms-2
25 ms-2
Correct answer is A
Acceleration = (increase in velocity)/time taken
= (45 - 25)/10 = (20)/10 = 2ms-2
the feather will be blown away by the wind while stone will drop steadily
the stone and the feather will both reach the ground at the same time
the feather will reach the ground first
the stone will reach the ground first
Correct answer is B
The acceleration of free fall due to gravity is independent of mass of the body. Therefore, ignoring air resistance, which affects feather more than the stone, the stone and the feather will both reach the ground at the same time