Question

1. How does the acceleration compare for an object in free fall when an it is thrown up versus thrown down? a.The acceleration is faster when it is thrown up compared to thrown down. b.The acceleration is positive when it is thrown up and negative when it is thrown down. c.The acceleration is slower when it is thrown up compared to thrown down. d.The acceleration is the same regardless of being thrown up or thrown down.
2. A textbook is dropped from the second story stairs and free falls to the ground. What changes, if any, would be observed of the velocity and the acceleration of the textbook as it falls?a.The velocity decreases b.The velocity increases c.The acceleration remains constantd. Both B & C

Answer 1

Answer:

1) Option b. The acceleration is positive when it is thrown up and negative when it is thrown down.

2) Option d. Both B & C

Explanation:

Question 1)

Acceleration is defined as the rate of change of velocity with respect to time.

$a=\frac{v_{f}-v_{i}}{t}$

When an object is thrown up, its velocity is maximum at the initial point and decreases as the object moves up. Since, the velocity is decreasing, the acceleration will be negative. This can also be proven from the formula mentioned above. When the object is thrown up, initial velocity(vi) is maximum and the final velocity (v_f) is zero, as the object rests for a very tiny moment at its maximum point. This will give a negative numerator and hence the value of acceleration will be negative.

When an object is thrown down, its velocity is zero at the start of the motion and increases as the object falls down. Since, the velocity is increasing in this case, the acceleration will be positive.

Therefore, Option b, gives the correct answer.

Question 2)

When an object falls freely, it falls under the action of gravity under a constant acceleration known as gravitation acceleration. Gravitational acceleration is represented by g and is equal to 9.8 m/s².

Since, the textbook is falling freely, its acceleration will be constant i.e. equal to gravitational acceleration.

When the object falls down, with every second its velocity increases. The velocity in minimum(zero) at the start and is maximum just before the object hits the ground.

So, when the textbook is dropped, it will fall with constant acceleration and its velocity will be increasing.

Therefore, for this question, Both B and C are correct.

Answer 2

1.

Answer:

d.The acceleration is the same regardless of being thrown up or thrown down.

Explanation:

As we know that when object is in air then net force on object is given as

$F = F_g$

here we know that

$F_g = mg$

now we will have

$ma = mg$

so we can say

$a = g$

so in any case whenever object is in air its acceleration is vertically downwards and magnitude is equal to "g"

Answer:

Both B & C

Explanation:

As we know that when book is in free fall then due to weight of the book it will experience net downward force.

This force will exert

$F = mg$

now we know that

$a = g$

so while in free fall the acceleration due to gravity will remain constant on the book but speed will increase

so we have

b.The velocity increases

c.The acceleration remains constant

d. Both B & C