Answer:
The moment of inertia will be increased by a factor of 1575
Explanation:
Let the moment of inertia of a wheel be given as;

where;
I is the moment of inertia of the wheel
m is mass of the wheel
r is radius of the wheel
when the mass is increased by a factor of 7 and the radius is increased by a factor of 15
Thus, the moment of inertia will be increased by a factor of 1575
Answer:
a)
, b) 
Explanation:
a) According to the Principle of Energy Conservation, the kinetic energy of the box is transformed into elastic potential energy.

The spring constant is:

b) The initial speed needed to compress the spring by 1.5 centimeters is:


Answer:
B
Explanation:
Torque exerted on an object depends upon three things.
1. Moment arm
2. Magnitude of applied force
3. Direction of force
T=r x F
T= r * F sinФ
Let T1 is force due to force applied at mid point of door.
let d is the width of door, so
T1=
°) (∴ moment arm =d)
T1=
__________(2) (∴ sin 90°=1)
Let T2 is the torque due to force applied at the doorknob.
T2=
(∴ moment arm =d)
T2=
__________(2) (∴ sin 90°=1)
From equation (1) and equation (2)
2T1=T2
or
T1= T2/2
As T2 is greater so option B is the correct answer.