Olympiad Test: Gravitation- 1 - Class 9 MCQ

According to the Archimedes’ principle the buoyant force acting on this ball B will be equal to the weight of water displaced by this

ball. Weight = m ×g

and m = volume × density

∴ Ball b has maximum volume of liquid (24 mL) displaced .

V2= u2+ 2gh, u = 0

V=⅙

√(2gh)=√(2×9.8×100)=√1960 =44.2 M/s

gmoon =(⅙)gearth

= (⅙)× 10 = 1.66 m/s2

When breadth and height form the base, wooden block is standing vertically to the ground, exerting maximum pressure due to minimum area covered

l = 50, b = 25, h = 10

Area 1= l ×b = 1250 cm2

Area 2 = l × h = 50 × 10 = 500 cm2

Area 3 = b × h = 25 × 10 = 250 cm2

Area 3 is the minimum, and pressure = Area/Force

Relative density of iron is 7.8 and that of mercury is 13.6. Thus, mercury is heavier than iron.

Weight = mg

m = 120 kg g on moon = (⅙) × g on earth

= (⅙) × 9.8

∴ weight = 120 × (⅙) × 9.8 = 2 × 98 = 196 N

u = 15, v = 0, g = –9.8

v2 = u2 + 2gh

02 = (15)2 + 2(–9.8) h

⇒ h = 11.4m

F = G (m1m2/r2 )

V = u + at

u = 0, a = g = 9.8 ms2, t = 2 s

v = 2 × 9.8 = 19.6 ms–1