LHTB Physics Pre-Exam (2.3a. Mechanics – Dynamics)

As an object slides down a slope, its…

• kinetic energy increases and its potential energy increases

• kinetic energy decreases and its potential energy increases

• kinetic energy increases and its potential energy decreases

A single fixed pulley (discounting friction etc) has a mechanical advantage of...

• 2

• 1/2

• 1

What is the ratio of load to effort called?

• Mechanical advantage

• Velocity ratio

• Mechanical ratio

1 kW is…

• 3413 BTU per hour

• 360 joules

• 1.56 HP

The tension in the cable of a crane is 2500 N and it lifts a load through 50m, what is the work done on the load?

• 500 J

• 12.5 kJ

• 1.25 * 10 J5

What is the kinetic energy of an aircraft of mass of 2 metric tonnes and has a velocity of 2m/s?

• 8kJ

• 4kJ

• 2kJ

The work done in lifting a mass of 2000 kg vertically to a height of 40 metres is.

• 80 kJ

• 784.8 kJ

• 400 kJ

If a machine has a mechanical advantage of 10 and a velocity ratio of 20. The efficiency of the machine is...

• 200%

• 2

• 0.5

1 Watt =

• 1 Joule/s

• 1 HP

• 1 kg/h

How would you work out the work done by a machine assuming it is 100% efficient?

• Mechanical advantage and input

• Mechanical advantage and output

• Input and output