# 9-1 Topic 3 Energy

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### A 60 kg student weighs 600 N. He does a bungee jump. The bungee cord becomes straight and starts to stretch when he has fallen 50 m. He first stops moving: • before all the energy has disappeared
• before the bungee cord starts to stretch
• when the bungee cord is stretched the most
• when the elastic potential energy is zero

• 600 kg m/s
• 3 000 kg m/s
• 6 000 N m/s
• 30 000 N m/s

### The roller coaster car rolls down towards P. The car has mass, m kg and velocity v m/s. Which of these is the correct equation for calculating the kinetic energy of the car? • KE = mv
• KE = mv2
• KE = ½mv2
• KE = 2mv2

### The diagram shows a girl swinging a rubber ball in a horizontal circle above her head. In which direction does the resultant force act on the ball? • away from the centre of the circle
• in the direction of the arrow on the diagram
• in the opposite direction to the arrow on the diagram
• towards the centre of the circle

### Some students investigate the efficiency of electric motors. One of the students states that all of the energy supplied to a motor is transferred into other forms. This statement is one example of the idea of:

• renewable energy
• conservation of energy
• non-renewable energy
• sustainable energy

### A pilot begins to land an aircraft. The height of the aircraft decreases from 200 m above the ground to 100 m. What happens to the gravitational potential energy of the aircraft?

• it becomes zero
• it decreases
• it does not change
• it increases

### The velocity of the aircraft remains constant. What happens to the kinetic energy of the aircraft?

• it becomes zero
• it decreases
• it does not change
• it increases

### The International Space Station (ISS) has several solar panels called wings. The wings convert energy from the Sun into a form useful in the ISS. • transverse and electromagnetic
• electromagnetic but not transverse
• transverse but not electromagnetic
• neither transverse nor electromagnetic

• current
• energy
• voltage
• charge

### In many sports events, an athlete tries to throw an object as far as possible. Sport scientists can use many words to describe the throwing of an object but which of these is a vector: • energy
• momentum
• power
• speed