Electrical Science 4 - Force mass Acceleration

Fill in the Blanks

If a force of 10 N is applied to an object and it moves a distance of 5 meters, what is the work done? Use significant figures and units.

Open Ended

If you have a balloon and a bowling ball, which object would need more force to make it move. Explain why. (answer in complete sentences)

Fill in the Blanks

The graph below represents the speed of a marble rolling down a straight incline as a function of time.

What quantity is represented by the slope of the graph?

Multiple Choice

A vehicle accelerates from 10 m/s to 30 m/s in 4 seconds. What is its average acceleration?

• 4 m/s²

• 5 m/s²

• 6 m/s²

• 7 m/s²

Multiple Choice

Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object).

• Newton's 1st Law
• Newton's 2nd Law
• Newton's 3rd Law
• None of them

Multiple Choice

A pallet of trunking has a mass of 700kg. What force will be required to lift it?

• 5.867 kN

• 6.867 kN

• 7.867 kN

• 8.867 kN

Fill in the Blanks

A crane uses an average force of 5200 N to lift a girder 25 m. How much work does the crane do on the girder?

W =

J

Multiple Choice

Calculate the potential energy of a car with a mass of 2,500 kg that is on a hill 100 meters above sea level.

• 250,000 J

• 2,450,000 J

• 2,451,663 J

• 248 J

Multiple Choice

What is the formula for calculating the efficiency of a system?

• Output power = input power + losses

• Input power = output power - losses

• Efficiency = output power / input power

• Efficiency = input power / output power

Multiple Choice

Calculate the input power required for each level of efficiency of a motor producing 1kW of output power and is:

• 50% efficient

• 70% efficient

• 100% efficient

• 30% efficient

Multiple Choice

What is the formula for calculating input power based on efficiency?

• Input power = output power / efficiency

• Input power = efficiency / output power

• Input power = output power * efficiency

• Input power = efficiency * 100

Multiple Choice

If the efficiency of a machine is 70%, what is the input power if the output power is 1000 watts?

• 1000 watts

• 1429 watts

• 500 watts

• 2000 watts

Multiple Choice

An electric motor drives a pump that lifts 1000 litres of water each minute to a tank 20 metres above ground level. Calculate the power the motor must provide if the pump is 50% efficient.

• 196200 watts

• 3270 watts

• 1000 watts

• 500 watts

Open Ended

Calculate the input power if the output power is 3270 watts and the efficiency is 50%.

Fill in the Blanks

Which class of lever is represented by the picture on the left?

Multiple Choice

A camera boom is used at a television studio to allow filming from different positions.

Complete the sentence.

When the moment caused by the weight of the camera increases, the moment caused by the counterweight ____________________ .

• decreases

• does not change

• increases

• They are all the same moment.

Multiple Choice

A crowbar is used to lift a packing case. The load exerted by the packing case is 900N. Determine the effort needed to lift the packing case, if the load is 15cm from pivot and the effort is 1.2m from the pivot. What is the effort required?

• 112.5N

• 150N

• 75N

• 90N

Multiple Choice

What is the mechanical advantage of a pulley system that looks like this?

• 5

• 8

• 1

• 2

Open Ended

Any questions?

Poll

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