Physics Conceptual Question? Newton's Law?

Question

If aperson were to take a large student and a small student to the top of the building and push them both off the building with equal force:

n  Which one would hit the ground first?

n  Which one would make the bigger dent in the ground?

n  Which one would land the furthest  from the face of the building?

Give your reasoning.

Answer 1

Step 1:

Two student of different masses are pushed from a top of the building.

There are two environments to observe the situation.  In a vacuum,the friction is absent, so both objects will fall at the same time.

Surface area and mass become important on our earth.  On earth where every object experiences gravity, the two objects will fall at different rates. 

Let us consider the weight of the small student is x .

Let the weight of large student is 2x.    (Since large student weighs more than small student)

Acceleration due to gravity= 9.8 m/s².

Downward force being exerted by object is : F = mass x acceleration due to gravity .

Downward force being exerted by small student :  F = (x) x (9.8m/s²) = 98x N.

Downward force being exerted by large student : F =(2x) x (9.8m/s²) = 196x N.

Therefore, the larger student will hit the ground first.

Solution :

The larger student will hit the ground first.

 

Answer 2

(2)

Step 1:

Two student of different masses are pushed from a top of the building.

Dent ( hollow ) in the ground caused by the object is proportional to the work done by the object.

Work done  = force  x distance .

Force = mass x acceleration due to gravity .

Distance travelled by the large student and small student is equal.

Acceleration due to gravity is same for large student and small student is equal (g = 9.8 m/s² ).

Let us consider the weight of the small student is x .

Let the weight of large student is 2x.    (Since large student weighs more than small student)

Let the distance travelled by the large student and small student is d.

Small student :

Work done  =  (x) * (g) * (d) = 9.8 dx  N .

Large student :

Work done  =  (2x) * (g) * (d) = 19.6 dx  N .

Therefore, large student will dent more than the small student.

Solution :

Large student will make bigger dent.