a body is projected at an angle of 30 degree with the horizontal so that it's time of flight is 10 second. Find the speed of the projection of body.
Time of flight T=u×sin30/g
T=10s
10=u×sin30/g
u=10 ×g÷1/2
u=20×g=196m/s
The angle made by velocity vector with the horizontal after 1.5 s is zero
Explanation:
Initial velocity of the body u = 30 m/s
Angle of projection = 30°
Horizontal component of the velocity = ucos30° = 30 × √3/2 = 15√3 m/s
Vertical component of the velocity = usin30° = 30 × 1/2 = 15 m/s
The acceleration due to gravity is acting only in the vertical direction
Therefore, only the vertical component of the velocity will change
Using the first equation of motion
If the vertical component of the velocity after 1.5 seconds is v then
v = u - gt
v = 15 - 10 × 1.5
= 15 - 15
= 0
Therefore, after 1.5 seconds, the body will have only horizontal velocity
Hence the Angle made by velocity vector with the horizontal = 0
Hope the answer is helpful.
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