Answer:
C. -12 ab
Explanation:
The restoring force on a spring is given by Hooke's law:
where
k is the spring constant
x is the stretched (or compressed) displacement of the spring
In this problem we have:
k = 4a
x = 3b
Substituting into the equation, we find:
And the negative sign means that the direction of the force (negative) is opposite to the direction of the displacement (positive).
Answer:
kinetic friction may be greater than 400 N or smaller than 400 N
Explanation:
As we know that maximum value of static friction on the rough surface is known as limiting friction and the formula of this limiting friction is known as
now when object is sliding on the rough surface then the friction force on that surface is known as kinetic friction and the formula of kinetic friction is known as
now we know that
so here value of limiting static friction force is always more than kinetic friction
also we know that
initially when body is at rest then static friction value will lie from 0 N to maximum limiting friction
and hence kinetic friction may be greater than static friction or if the static friction is maximum limiting friction then kinetic friction is smaller than static friction
so kinetic friction may be greater than 400 N or smaller than 400 N
Here we apply conservation of linear momentum. The momentum of the truck with cargo and without cargo remains constant. That is,
.
Here are initial mass and velocity.
are final mass and velocity. Here
and
.
The velocity of the truck be after its cargo is taken off is