L6th Homework Quiz 3

Which of the following is a scalar quantity?

• velocity

• kinetic energy

• force

• momentum

Three identical cells, each of internal resistance R, are connected in series with an external resistor of resistance R. The current in the external resistor is I. If one cell is reversed in the circuit, what is the new current in the external resistor?

• $\frac{I}{3}$

• $\frac{4I}{9}$

• $\frac{I}{2}$

• $\frac{2I}{3}$

A cylindrical conductor of length l, diameter D, and resistivity  $\rho$   and has resistance R. What is the resistance of another electrical conductor of length l, diameter  $\frac{D}{2}$  , and resistivity  $\rho$  ?

• 8R

• 4R

• 2R

• R

Which of the following is NOT a unit for power?

• Nms^-1

• kgm²s^-3

• Js^-1

• kgm^-1s^-1

Two forces, 6N and 10N act at a point. Which could NOT be a magnitude of the result?

• 16 N

• 8 N

• 5 N

• 3 N

The unit of potential difference can be expressed as

• Cs^-1

• JC^-1

• VA^-1

• JA^-1

A skydiver of mass 80 kg falls vertically with a constant speed of 50 m s^–1. The upward force acting on the skydiver is approximately

• 0 N

• 80 N

• 800 N

• 4000 N

Which of the following is a correct statement of Newton’s second law of motion?

• A force acting on a body is proportional to the mass of the body.

• The rate of change of momentum of a body is equal to the net external force acting on the body.

• The momentum of a body is proportional to the net external force acting on the body.

• A force acting on a body is proportional to the acceleration of the body.

Which of the following quantities can be determined from a speed-time graph of a particle travelling in a straight line?

• Only the magnitude of the acceleration at a given instant

• Both the velocity and the acceleration at a given instant

• Only the distance travelled in a given time

• Both the distance travelled in a given time and the magnitude of the acceleration at a given instant

Which of the following may be determined from a speed-time graph?

• Displacement

• Distance

• Power

• Force