Principles of basic mechanics - Outcome 4

The work needed to raise a load of 95kg to a height of 30 m is approximately

• 28 J

• 2.79 kJ

• 28 kJ

• 285 J

The pivot point of a lever is called

• centre

• pulley

• Load

• fulcrum

A motor has an input power of 3 kW and is 85 % efficient. What is the output power?

• 2.55 kW

• 3 kW

• 3.53 kW

• 2.4 kW

If an object has a mass of 50 Kg on earth, in space its mass would be

• 100 kg

• 490 kg

• 50 kg

• 41 kg

What is the power of a hoist required to lift an object of 20 kg, 20 m in 30 seconds.

• 3.3kW

• 1.3kW

• 13.3W

• 130.8W

Pliers rely on which principle for their operation

• leverage

• tension

• torsion

• friction

A motor has an input power of 50kW and an output power of 47kW. What is the efficiency of the motor?

• 100 %

• 86 %

• 96 %

• 94 %

A motor has an output power of 40kW and an efficiency of 80%. What is the input power of the motor?

• 32 kW

• 50 kW

• 40 kW

• 54 kW

The power input to a machine is 90 W and the output power is 60 W the efficiency of the machine is

• 86 %

• 66.6 %

• 75 %

• 80 %

The weight of an object is the

• mass of the object divided by 9.81

• the same as the mass when there is gravity

• force acting on top of the object due to gravity

• force acting directly below the object due to gravity

A mass of 9.5 Kg exerts a force on earth of

• 9.3 N

• 95 N

• 9.5 N

• 93.2 N

What is the power of a motor required to lift a load of mass 300kg 40m in 2 minutes.

• 981 W

• 6000 W

• 98.1 W

• 100 W

A motor has an output power of 40kW and an efficiency of 66.66%. What is the input power of the motor?

• 30 kW

• 60 kW

• 50 kW

• 70 kW

A 2kW heater is 90% efficient. The input power to the heater is

• 5kW

• 1.88kW

• 3kW

• 2.22kW

A mass of 30kg would have an weight of

• 0.327N

• 3.05kN

• 3.05N

• 294.3N

A motor has an efficiency of 73%. If the input power is 32kW, the output power available is

• 76.64kW

• 23.36kW

• 22.8kW

• 32kW

Calculate the work done when required to raise a load of 1000kg through a vertical distance of 20m.

• 19620J

• 20000J

• 200000J

• 196200J

A force of 50kN moves an object a distance of 2m. The work done is.

• 25kJ

• 50kJ

• 100kJ

• 200kJ

What is the relationship between force, mass and acceleration?

• f = ma

• f = m/a

• f = m - a

• f = m + a

What is the work done when a force of 30N move an object 10m

• 200 metres

• 300 Horse power

• 300 Watts

• 300 Joules

What is the gravitational pull on earth

The force of gravity on earth is considered to be

A load of 50Kg has a force of 25N applied what is the acceleration of the load