From the top of a 11m high tower, a stone is projected with speed 10m/s, at an angle of 37∘ with the horizontal as shown in the figure. Find a) Time of flight. b) Horizontal range. c) Speed just before striking the ground. (Take g=10m/s2)
A
(a) 115s, (b) 885m, (c) 8√5m/s
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
(a) 1s, (b) 8m, (c) 8√5m/s
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
C
(a) 115s, (b) 885m, (c) 4√5m/s
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
(a) 1s, (b) 8m, (c) 4√5m/s
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution
The correct option is B (a) 1s, (b) 8m, (c) 8√5m/s ux=10cos37∘=8m/s,uy=−10sin37∘=−6m/s
a) Using second equation of motion Sy=uyt+12ayt2⇒−11=−6×t+1/2×(−10)t2 ⇒5t2+6t−11=0 ⇒(t−1)(5t+11)=0 ⇒t=1sec (taking positive value)
b) Range =ux×t=8×1=8m
c) Speed just before striking the ground v=√v2x+v2y=√u2x+u2y+2gh=√(8)2+(6)2+2×(−10)×(−11)=√100+2×10×11 ⇒v=√320m/s=8√5m/s