oscillation
resonance
swinging
vibration
Correct answer is B
Marching soldiers crossing a suspension bridge are usually advised to break their steps to avoid damaging the bridge owing to resonance. The steps of the marching soldiers can set the bridge into vibration, and when the frequency of the bridge is equal to that of the steps of the soldiers, the resonance occurs,and at this resonance, the bridge vibrates violently with maximum amplitude, and can collapse.
102N
70N
140N
112N
Correct answer is D
Pressure = Force / Area = Weight of the man / Area of his feet
=> 2.8 x 103 = Weight of the man / 4 x 10-2
∴ Weight of the man = 2.8 x 103 x 4 x 10-2
= 112N
Transverse waves can be distinguished from longitudinal waves using the characteristic of
diffraction
refraction
polarization
reflection
Correct answer is C
No explanation has been provided for this answer.
0.20m
0.22m
0.25m
0.02m
Correct answer is D
Safety gap = expansion of the rod
= \(\alpha \times L_0 \times \Delta t\)
where \(\alpha\) = linear expansivity of the material
\(L_0\) = Initial length of the material
\(\Delta t\) = Change in temperature
\(\therefore\) The safety gap = \(2 \times 10^{-5} \times 20 \times (75 - 25)\)
= \(2 \times 10^{-5} \times 10^3\)
= \(2 \times 10^{-2} m\)
= 0.02 m
400 J kg-1K-1
500 J kg-1K-1
390 J kg-1K-1
130 J kg-1K-1
Correct answer is B
Heat supplied by the heater in 10 mins
= power x time
= 50 x (10 x 60)
= 30000 J
This heat is equal = MCΔt
= 5 x c x 12
= 60cJ
= 60C = 30,000
C = 30,000/60
C = 500 J kg-1K-1