Question

A ball is thrown leftward from the left edge of the roof, at height h above the ground. The ball hits the ground 1.60 s later, at distance d = 20.0 m from the building and at angle θ = 66.0° with the horizontal. (a) Find h. (Hint: One way is to reverse the motion, as if on videotape.) What are the (b) magnitude and (c) angle relative to the horizontal of the velocity at which the ball is thrown (positive angle for above horizontal, negative for below)? No figure is given.

Answer 1

Here, k is di electric constant v 10.0 V 57 3.3 Use the hint, treat this problem as time reversed problem So use the coordinate system with +x as rightward and positive angles measured counterclockwise Write the equation 20 mm vcos(66) 1.6s)) v 30.73 m/s sin 66° 30.73sin 66 28.073 m/s Substitutev, in equation (1) y-(0) 28.073x(1.6)-(9.8)(1.6) 44.92-12.56 y-32.36 m

b) v32.36)(cos 66) 13.1633 m/s y,-Vy-gt-G0.73x sin 66)-(9.81 x 1.6)-12.38 m / s To find out the magnitude of M M+v-13.1633 +1238-18.07m/s c) Calculate the angle made by the ball 12.38 d) Using the result as an initial velocity of magnitude 18.07 m/s with an angle of 43.24° (down from leftward)