Question
Physics Question on Motion in a plane
A stone is thrown at 25m/s at 53o above the horizontal. At what time its velocity is at 45o below the horizontal?
A
0.5s
B
4s
C
3.5s
D
2.5s
Answer
3.5s
Explanation
Solution
Horizontal component of velocity, throughout the motion remain constant using ucosθ=vcosα 25cos53∘=vcos?45∘ ⟹v=25×53.2 =152 ⟹vy=vsin45=15 Now using Vy=uy+aytiny− direction, −15=25sin53? −15=25×54−10t ⟹t=3.5sec