1.) Which of the following statements concerning network is always true? A.) Wne

Question

1.) Which of the following statements concerning network is always true?

A.) Wnet= change in potential energy

B.) Wnet= change in kinetic energy

C.) Wnet= change in elastic potential energy

D.) Wnet= change in total mechanical energy

E.) Wnet= zero

2.) How much power is required to lift a 3kg stone to a height of 5m in 0.5 seconds?

A. 6W

B. 15W

C. 30 W

D. 300 W

E. None of the above

3.) What is the most accurate statement concerning the spring constant (k)?

         A. The spring constant is the ratio of the displacement of the spring from its equilibrium position divided by the force applied to the spring

         B. When the displacement of the spring from its equilibrium position is plotted (y-axis) against the force applied to the spring that caused

            C. Spring constant is a unitless number related to the “stiffness” or strength of the spring.

            D Spring constant is the ratio of the force applied to the spring divided by the displacement of the spring from its equilibrium position that results

            E. Spring constant has SI units of Newton-meters (N-m) and is related to the “stiffness” or strength of the spring.

4.) What is the most accurate statement concerning Bernoullis Equations? (p + ½ pv^2 + pgh = constant

            A. Bernoullis equation applies to both laminar and turbulent fluid flow

            B. Bernoulli’s equation only applies when the gravitational potential energy of the fluid remains constant

            C. Bernoulli’s equation is derived from the law of conservation of energy

            D. Bernoulli’s equation is derived from the law on conservation of momentum

            E. Bernoulli’s equation can only be applied to water flowing in a pipe f the cross-sectional area of a pipe remains constant

5.) Water flowing through a pipe with diameter d has a volume flow rate of Q. If the diameter of the pipe halves (d/2). What is the new volume flow rate?

            A. Q

            B. 2 Q

            C. 1/2 Q

            D. 4 Q

            E. ¼ Q

6.) A child stands on the outer edge of a merry-go-round (a flat disc that rotates in lace while parallel to the ground – see below) The entire system initially rotates

            A. The angular velocity will increase because the total moment of inertia has decreased.

            B. The angular velocity will increase because the total moment of inertia has increased

            C. The angular velocity will decrease because the total moment of inertia has decreased.

            D. The angular velocity will decrease because the total moment of inertia has increased.

            E. The angular velocity will remain constant.

7.) A 20.0 kg flywheel rotates with an initial angular speed of 20 rad/s. The flywheels moment of inertia in N-m is?

Explanation / Answer

1) if non conservation forces are acting on the system then

Wnet = change in total mechanical energy

So the always true statemet is

Wnet = change in total mechanical energy

2) Power is P = work done / time taken = (m*g*h)/t = (3*10*5)/0.5 = 300 W

so correct answer is D. 300 W

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