A-projectile-is-fired-at-an-angle-with-the-horizontal-direction-from-O-Neglecting-the-air-friction-it-hits-the-ground-at-B-after-3-seconds-What-is-the-height-of-point-A-from-ground-Use-g-10-m

FacebookTweetPin

Question Number 16150 by Tinkutara last updated on 18/Jun/17

$$\mathrm{A}\mathrm{projectile}\mathrm{is}\mathrm{fired}\mathrm{at}\mathrm{an}\mathrm{angle}\theta \mathrm{with}$$$$\mathrm{the}\mathrm{horizontal}\mathrm{direction}\mathrm{from}O.$$$$\mathrm{Neglecting}\mathrm{the}\mathrm{air}\mathrm{friction},\mathrm{it}\mathrm{hits}\mathrm{the}$$$$\mathrm{ground}\mathrm{at}B\mathrm{after}3\mathrm{seconds}.\mathrm{What}\mathrm{is}$$$$\mathrm{the}\mathrm{height}\mathrm{of}\mathrm{point}A\mathrm{from}\mathrm{ground}?$$$$[\mathrm{Use}g=10\mathrm{m}/{\mathrm{s}}^2]$$

Commented by Tinkutara last updated on 18/Jun/17

Answered by ajfour last updated on 18/Jun/17

$$lettimeofflight=T=3s$$$$T=\frac{2u\sin \theta }{g}\Rightarrow u\sin \theta =\frac{gT}{2}=15m/s$$$$OA=uT,AB=OA\sin \theta$$$$AB=\left(u\sin \theta \right)T$$$$=\left(15m/s\right)\left(3s\right)=45m.$$$$$$

Commented by Tinkutara last updated on 18/Jun/17

$$\mathrm{Thanks}\mathrm{Sir}!$$

Terms of Service
Privacy Policy
Contact: info@tinkutara.com

FacebookTweetPin