Question

A body is projected downward at an angle of 30° with the horizontal from the top of a building 170 m high. Its initial speed is 40 m/s. 2.49 (c) At what angle with the horizontal will it strike? (c) 60

Answer 1

The body will strike at angle 60.46°

Step-by-step explanation:

Vertical motion of body:

Initial speed, u = 40sin30 = 20m/s

Acceleration, a = 9.81 m/s²

Displacement, s = 170 m

We have equation of motion, v² = u² + 2as

Substituting

v² = 20² + 2 x 9.81 x 170

v = 61.12 m/s

Final vertical speed = 61.12 m/s

Final horizontal speed = initial horizontal speed = 40cos30= 34.64m/s

Final velocity = 34.64 i - 61.12 j m/s

Magnitude

`v=√(34.64^2+(-61.12)^2)=70.25m/s`

Direction

`\theta =tan^(-1)\left ( (-61.12)/(34.64)\right )=-60.46^0`

The body will strike at angle 60.46°