Mechanics (Electrical principles)

What is a good description of mass?

• Mass changes depending on where you are.

• Mass can be zero

• Mass is not related to gravity.

• the si unit for mass is the Newton

What is weight?

• The amount of ‘matter’ in an object

• The force exerted on an object by gravity.

• the distance an object moves with gravity

• The difference between the mass and the distance.

An object with a mass of 1.0 kilogram will weigh approximately what?

• 0.707 Newtons

• 0.636 Newtons

• 1 Newton

• 9.81 Newtons

Acceleration can be found by which formula?

• $\frac{final\ velocity\ \left(v\right)-initial\ velocity\ \left(u\right)}{time\ \left(t\right)}$

• $\frac{work\ done\ }{time\ taken\ }$

• $input-losses$

• $\frac{input}{efficiency}\times100$

What work must be done to lift a 600kg bundle of conduit from the floor on to a rack 3.25m high?

• 1950 Nm

• 19130 Nm

• 184.6 Nm

• 198.77 Nm

A motor produces 12000 watts output power and is 87.6% efficient what is the input power?

• 10.5 kW

• 16.4 kW

• 13.7 kW

• 18.8 kW

An electrician carries his tool box weighing 30 kg out to the van 30 meters away it takes 2 minutes. The next day he does the same thing but as he's in a rush it takes only 1 minute 30 seconds. which statement is correct?

• He used more power the second time

• Both took the same amount of power

• The first took more power

Calculate the distance covered by a forklift of 800 kg when the amount of work done is 12000 Nm.

• 9600 km

• 9 m

• 10 m

• 15 m

An object is moved across a distance of 330 m in 12 minutes by a force of 500N. Calculate the power used.

• 229.16 W

• 7.92 W

• 1980 kW

• 475.2 W

Calculate the power required to move a motor coil of 346N through a vertical distance of 8.7m in 24 seconds.

• 125.43 W

• 72.24 kW

• 14.42 W

• 106.32 W