Question

1-Toss a ball straight upward so that goes up and then back down. Throughout the flight, its acceleration is

Choix de groupe de réponses

in the direction of motion.

opposite its velocity.

directed upward.

directed downward.

2-

A volleyball player who remains airborne for a full 1 second must have jumped
Choix de groupe de réponses

about 0.8 m.

about 1 m.

about 1.2 m.

about 2.5 m.

3-

An apple falling from a tree 5 meters up hits the ground at about
Choix de groupe de réponses

5 m/s.

10 m/s.

15 m/s.

20 m/s.

Answer 1

1. directed downwards

2. about 1.2 m

3. 10 m/s

Explanation:

1. During Free fall, the acceleration remains constant. It is equal to 9.8 m/s^2 and its direction is always directed downwards.

So the answer is "directed downward".

2. From equation of motion.

u^2 = 2 x gh

u = g x t

t = sqrt (2 h/g)

h = t^2 g/2

t= 1/2 seconds

g = 9.8 m /s^2

Answer: h = 1.2 m

3. By conservation of energy

1/2mv^2 = mgh

v = sqrt (2 x gh)

h = 5m

g = 10 m/s^2

v = sqrt(2 x 10 x 5) = 10 m/s

So the answer is 10 m/s