work, energy and power

A 2 kg of mass was dropped from a height. If its maximum kinetic energy before it stroked the ground is 400 Joule, calculate its height dropped.

A machine is used to raise a mass of 250 kg to a height of 17 m within 15 seconds.

Calculate the power of the machine.

A battery converts what type of energy to another?

• sound to kinetic
• light to heat
• mechanical to electrical
• chemical to electrical

A force of 20 N is used to pull this box to the left for a distance of 100 m. What is the value of work done on the box?

• 1300.6 Joule

• 1519.4 Joule

• 2000.0 Joule

• 30 000 Joule

A picture of a plane of mass 80 000 kg is flying in the air at velocity of 900 kmh^-1. The height of the planes is 35 000 feet from the ground level.

Calculate it gravitational energy and kinetic energy at that time.

• PE = 2.74 x 10¹⁰ J, KE = 2.50 x 10⁹ J

• PE = 2.74 x 10¹⁰ J, KE = 3.24 x 10¹⁰ J

• PE = 8.37 x 10⁹ J, KE = 3.24 x 10¹⁰ J

• PE = 8.37 x 10⁹ J, KE = 2.50 x 10⁹ J

What type of energy is in this picture?

• Kinetic
• Potential
• Chemical
• Sound

A fan of power of 80 Watt has mass of the blades and motor of 1.2 kg. The fan blades moves at 18 ms^-1 in 45 seconds. Find the efficiency of the fan.

• 5.4 %

• 5.9 %

• 54 %

• 59 %

There are FOUR kids climbing the ladders. Given are their details of mass, height they climbed and the time they took.

Kid A = mass of 20 kg, height, h = 10 m, time, t = 60 s

Kid B = mass of 25 kg, height, h = 7 m, time, t = 30 s

Kid C = mass of 30 kg, height, h = 3 m, time, t = 20 s

Kid c = mass of 25kg, height, h = 0 m, time, t = 0 s

Which one of them have the highest body power of all?

• Kid A

• Kid B

• Kid C

• Kid D

The roller coaster car has a mass of 500 kg. It is pulled from position 1 to 2 (30 m) by a motor. At the top of the ride the vertical distance top to bottom is 20 m. The motor pulls the car with a 4000 N force. Calculate the work done getting the car to the top of the ride.

• 100 000J

• 120 000J

• 800 000J

• 90 000J

A battery converts what type of energy to another?

• sound to kinetic
• light to heat
• mechanical to electrical
• chemical to electrical