JAMB - Physics (2017 - No. 43)
Calculate the time taken for a mango fruit that fall from the tree 20 m to the ground [g = 10 ms-2]
10s
5s
4s
2s
ব্যাখ্যা
u = , H = 20, g = 10
From equation of motion under gravity
H = ut ± \(\frac{1}{2}\)gt2, It is falling so g is +ve
H = 0 + \(\frac{1}{2}\)gt2
H = \(\frac{1}{2}\)gt2
2H = gt2
\(\frac{2H}{g}\) = t2
t = \(\frac{\sqrt{2H}}{g}\)
= \(\frac{\sqrt {2 \times 20}}{10}\)
= √4
= 2s
From equation of motion under gravity
H = ut ± \(\frac{1}{2}\)gt2, It is falling so g is +ve
H = 0 + \(\frac{1}{2}\)gt2
H = \(\frac{1}{2}\)gt2
2H = gt2
\(\frac{2H}{g}\) = t2
t = \(\frac{\sqrt{2H}}{g}\)
= \(\frac{\sqrt {2 \times 20}}{10}\)
= √4
= 2s