Longtest

Which of the following is the correct SI unit of work?

• $kg\cdot m\ s^{-2}$

• $kg\cdot m^2s^{-1}$

• $kg\cdot m^2s^{-2}$

• $kg^2ms^{-2}$

If there is no motion, can work be done on a system?

• Yes, if an outside force is provided.

• Yes, since motion is only relative.

• No, since a system which is not moving has no energy.

• No, because of the way work is defined.

the amount of work you do if you push twice as hard against a stationary concrete wall

• doubles.

• is cut in half.

• remains constant but non zero.

• remains constant at zero.

How much work is done if you lift a 30N pail (with water) 3.0m vertically and then returned to its original position?

• 45J

• 90J

• 180J

• No work was done

On a Force versus position graph, the area under the curve represents

• work.

• kinetic energy.

• power.

• potential energy.

the quantity  $\frac{1}{2}mv^2$  is 

• the kinetic energy of the object.

• the potential energy of the object.

• the work done on the object by the force.

• the power supplied to the object by the force.

What is the objects kinetic energy if the net work done on an object is positive?

• decreases

• remains the same

• increases

• zero

What is the object's kinetic energy id the net work done on the object is negative?

• decreases

• remains the same

• increases

• zero

What is the object's kinetic energy if the net work done on the object is zero?

• decreases

• remains the same

• increases

• zero

the quantity $mgy$  is

• the kinetic energy of the object.

• the gravitaional potential energy of the object

• the work done on the object by the force.

• the power supplied to the object by the force.