Any change in velocity is called an acceleration. The rock is experiencing the gravitational force from the earth, accelerating it towards the ground.
Let original length be L. The new length is therefore 4L.
Let original cross sectional surface area of the wire be equal to πr^2.
This means original volume was L x πr^2 = Lπr^2
The volume is the same but the length is different so 4L x new surface area must be equal to Lπr^2. Let new surface area be equal to Y.
4L x Y = Lπr^2
=> Y = (πr^2 )/ 4
Using the resistivity formula,
R = pL/A. p which is resistivity is a constant so it stays the same
But this time, instead of L we have 4L and instead of πr^2 we have (πr^2)/4.
so the new resistance
= (4Lp)/ {(πr^2)/4}
= 16 (pL)/(πr^2)
= 16 (pL)/A. because πr^2 is A
since pL/A is equal to R from the formula, this is equal to
16 R.
R was 10 ohms
therefore new resistance is 16 x 10 = 160 ohms
Answer:
(B) 1.6 m/s^2
Explanation:
The equation of the forces acting on the box in the direction parallel to the slope is:
(1)
where
is the component of the weight parallel to the slope, with m = 6.0 kg being the mass of the box, g = 9.8 m/s^2 being the acceleration of gravity, 
being the angle of the incline
is the frictional force, with 
being the coefficient of kinetic friction, N being the normal reaction of the plane
a is the acceleration
The equation of the force along the direction perpendicular to the slope is
where 
is the component of the weight in the direction perpendicular to the slope. Solving for N,
Substituting into (1), solving for a, we find the acceleration:
Volume=mass/density
volume=455.6/19.3
volume=23.6 mL
