SIFT Physics and Simple Machines Questions and Answers 3

Question 1

A 200 N force is applied to a hydraulic piston with area 0.01 m². What pressure does this create in the fluid?

Accepted Answer

20,000 Pa

Answer

Pressure = Force / Area = 200 N / 0.01 m² = 20,000 Pa (Pascals).

Question 2

Which of Newton's Laws states that for every action there is an equal and opposite reaction?

Accepted Answer

Newton's Third Law (Action-Reaction)

Answer

Newton's Third Law states that for every action force, there is an equal and opposite reaction force. This explains rocket thrust, helicopter torque, and jet propulsion.

Question 3

What is the mechanical advantage of a wedge that is 12 cm long and 3 cm wide at its widest point?

Accepted Answer

4

Answer

MA of a wedge = length / width (at the thick end) = 12/3 = 4. A longer, thinner wedge has a higher mechanical advantage.

Question 4

An electric motor draws 5 A at 120 V. What is its power consumption?

Accepted Answer

600 W

Answer

Electrical power P = V × I = 120 × 5 = 600 W. This is the rate of electrical energy consumption.

Question 5

What is 'mechanical efficiency' in a machine?

Accepted Answer

The ratio of output power to input power, expressed as a percentage

Answer

Mechanical efficiency = (Work output / Work input) × 100%. No machine is 100% efficient due to friction and other losses.

SIFT Exam Practice Test

SIFT Exam Practice Test

SIFT Physics and Simple Machines Questions and Answers 3