Answer:
(1) t = 4.29 s
(2) h = 58.98 m
(3) v = 20.04 m/s (downward)
(4) h = 0.94 m
(5) v = 18.78 m/s
Explanation:
Assumption:
- during downward motion, acceleration due to gravity, g is positive. (+g)
- during upward motion, acceleration due to gravity, g is negative. (-g)
(1)
initial velocity of the baseball, u = 42.0 m/s
final velocity of the ball, v = 0
time of flight is given by;
v = u -gt
gt = u
t = u / g
t = 42 /9.8
t = 4.29 s
(2)
Given;
initial velocity of the golf, u = 0
final velocity of the golf, v = 34 m/s
the height of the cliff is given by;
v² = u² + 2gh
v² = 0 + 2gh
h = v²/2g
h = (34)²/(2x9.8)
h = 58.98 m
(3)
Given;
initial velocity of the rocket, u = 27 m/s
time of motion, t = 4.8s
final velocity, v = ?
v = u + gt
v = 27 + (-9.8 x 4.8)
v = 27 - 47.04
v = -20.04 m/s (the negative sign indicates downward motion of the rocket after 4.8 s)
(4)
Given;
initial velocity of the lizard, u = 4.3 m/s
final velocity of the lizard at maximum height, v = 0
the height rose by the lizard is given by;
v² = u² + 2(-g)h
0 = u² - 2gh
2gh = u²
h = u² / 2g
h = (4.3)²/(2 x 9.8)
h = 0.94 m
(5)
Given;
initial velocity of the person on the bridge, u = 0
height of the bridge, h = 18 m
final velocity of the person is the velocity at impact, v = ?
v² = u² + 2gh
v² = 0 + 2gh
v² = 2gh
v = √2gh
v = √(2 x 9.8 x 18)
v = 18.78 m/s
