Sally walks 10 meters forward and then 5 meters backwards. Which statement most accurate describes the magnitude of her displacement and distance travelled?
A) Sally's displacement is 5m less than her distance travelled.
B) Sally's displacement is 10m less than her distance travelled.
C) Sally's displacement is 5m greater than her distance travelled.
D) Sally's displacement is 10m greater than her distance travelled.

Free fall is a situation in which the only force acting upon an object is gravity. Why do all objects in free fall have the same acceleration?
A) their masses are always the same
B) acceleration due to gravity is always the same
C) the distance between two objects is always the same
D) the gravitational force between two objects are always the same

- Distance is the total distance travelled by Sally, regardless of her direction. In this case, Sally has travelled 10 meters forward and then 5 meters backward, so the distance travelled is

[tex]d = 10 m + 5 m=15 m[/tex]

- Displacement, instead, is the difference between the final position and the initial position of Sally, which means that we have to calculate the vector sum of all the movements made by Sally. Assuming 'forward' as positive direction, this means that Sally's displacement will be:

[tex]d = 10 m +(-5 m)=+5 m[/tex] (forward)

Therefore, we can conclude that Sally's displacement (5 m) is 5 m less than her distance travelled (10 m).

2. B) acceleration due to gravity is always the same

According to Newton's second law:

[tex]F=ma[/tex]

by re-arranging it, we find the acceleration of an object:

[tex]a=\frac{F}{m}[/tex] (1)

The only force acting on an object in free fall is the gravity, so [tex]F=mg[/tex], where m is the mass of the object and g is the acceleration due to gravity. Substituting into (1):

[tex]a=\frac{mg}{m}=g[/tex]

So, the acceleration of an object in free fall does not depend on the mass of the object, but only on the value of g, which is the same for every object.

bc160402048 bc160402048 · Answer 2 · 2019-01-27T14:44:11+01:00

Answer#1

option B) Sally's displacement is 10m less than her distance travelled.

is the correct option of this Question

Explanation

Distance can be described as a scalar quantity that refers to "how much ground an object has covered" during its motion.

on the other hand Displacement is a vector quantity that refers to "how far out of place an object is"; it is the object's overall change in position.

Distance=10m+5m=15m

Displacement=10m+(-5)m=5m

difference between distance and displacement is 15-5=10

hence option B) Sally's displacement is 10m less than her distance travelled is the correct option

Answer#2

option B) acceleration due to gravity is always the same

is the correct option of this question

Explanation:

by newton's second law

f=ma

a=[tex]\frac{f}{m}[/tex]............(1)

The only force acting on an object in free fall is the gravity,

so F=mg,

here m is the mass

and g acceleration due to gravity.

putting this in (1)

we get

a=[tex]\frac{mg}{m}[/tex]

a=g

hence proved that acceleration of an object in the free falldoes not depend upon mass of an object