Answer:
D)Not enough information
Explanation:
According to Pascal's principle, the pressure exerted on the two pistons is equal:

Pressure is given by the ratio between force F and area A, so we can write

The force exerted on each piston is just equal to the weight of the corresponding mass:
, where m is the mass and g is the gravitational acceleration. So the equation becomes

Now we can rewrite the mass as the product of volume, V, times density, d:

We also know that 
So we can further re-arrange the equation (and simplify g as well):


We are also told that block B has bigger volume than block A:
. However, this information is not enough to allow us to say if the fraction on the right is greater than 1 or smaller than 1: therefore, we cannot conclude anything about the densities of the two objects.
The answer & explanation for this question is given in the attachment below.
Answer:
amount of work done, W = 549.36 kJ
Given:
mass of a car engine, m = 2500 kg
initial velocity, u = 45 mph
final velocity, v = 65 mph
1 mile = 1609
Solution:
We know that 1 hour = 3600 s
Now, velocities in m/s are given as:
u = 45 mph =
= 20.11 m/s
v = 65 mph =
= 29.05 m/s
Now, the amount of work done, W is given by the change in kinetic energy of the car and is given by:
W = 
W = 
W = 
W = 549.36 kJ