Question

A player kicks a football with an initial speed of $25\, ms ^{-1}$ at an angle of $45^{\circ}$ from the ground. What are the maximum height and the time taken by the football to reach at the highest point during motion ? (Take $g =10 \,ms ^{-2}$ )

• A. $h _{\max }=10 \,m \,T =2.5 \,s$
• B. $h _{\max }=15.625\, m \,T =3.54 \,s$
• C. $h _{\max }=15.625\, m \,T =1.77\, s$
• D. $h _{\max }=3.54\, m \,T =0.125 \,s$

Answer 1

Answer: (C)

$H =\frac{ U ^{2} \sin ^{2} \theta}{2 g } $
$=\frac{(25)^{2} \cdot(\sin 45)^{2}}{2 \times 10} $
$=15.625\, m $
$T =\frac{ U \sin \theta}{ g } $
$=\frac{25 \times \sin 45^{\circ}}{10} $
$=2.5 \times 0.7 $
$=1.77 \,s$