Question

a student throws a rock horizontally from the edge of a cliff that is 20 m high. the rock has an initial speed of 10 m/s. if air resistance is negligible, the distance from the base of the cliff to where the rock hits the level ground below the cliff is most nearly

Answer 1

Answer:

40m

Explanation:

u=10m/s, h=20m, g=?, s=h, v=0

solve for g first

v²=u²+2gs

0=10²+2×g×20

0=100+40g

-100=40g

g=-2.5m/s²

solve for time t

v=u+gt

0=10+(-2.5t)

-10=-2.5t

divide both side by -2.5

-10/-2.5=t

t=4s

lastly, solve for x(distance)

x=ut+1/2gt²

x=10×4+1/2×2.5×16

x=40+(2.5×8)

x=40+20=60

then subtract the d1(initial) from d2(final) distance

x=60-20=40m