5) A ball is kicked with a speed of 45 m/s from the top of a tower 170 m high. T

Question

5) A ball is kicked with a speed of 45 m/s from the top of a tower 170 m high. The ball falls of the edge and drops to the ground below. What is the speed of the ball on reaching the ground, (g = 9.8 m/s2and air resistance is negligible)? a. 39 m/s b. 58 m/s c. 45 m/s d. 70 m/s 6) A ball is kicked with a speed of 45 m/s from the top of a tower 170 m high. The ball falls of the edge and drops to the ground below. How long does it take for the ball to reach the ground, (g = 9.8 m/s2and air resistance is negligible)? a. 3.9 s b. 6.8 s c. 4.5 s d. 5.9 s 7) A ball is kicked with a speed of 45 m/s from the top of a tower 170 m high. The ball falls of the edge and drops to the ground below. How far from the base of the tower does the ball fall, (g = 9.8 m/s2and air resistance is negligible)? a. 265 m b. 170 m c. 202 m d. zero

Explanation / Answer

5) d) 70 m/s

we know,
vx = vox = 45 m/s

vy = sqrt(2*g*h)

= sqrt(2*9.8*170)

= 57.7 m/s

v = sqrt(vx^2 + vy^2)

= sqrt(45^2 + 57.7^2)

= 73 m/s

6) d. 5.9 s

let t is the time taken, h = 0.5*g*t^2

==> t = sqrt(2*h/g)

= sqrt(2*170/9.8)

= 5.9 s

7) a.265 m

x = vox*t

= 45*5.9

= 265 m

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