4the aviation department at the old coleman avenue facility had a small supersonic wind tunnel with a test section 1 inch in height. the operating conditions were such that the reservoir pressure and temperature were 1,2000r and 8 atmospheres. the exit temperature of the tunnel was 9500r. the mass flow rate through the tunnel was 0.5 slug/s. using the energy equation and isentropic relations, determine the reservoir density, exit velocity, exit density, exit pressure and exit area. for air, cp = 6,000 ft lb/slug 0r. assume standard sea level conditions.

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.

3. dark matter

empty space could also be a simple vacuum

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.