1.1 What is energy? - Word problems

1. Jenny is running on a treadmill. She measures the energy she burns in joules (J). In 5 minutes, she burns 500 J of energy. How many kilojoules (kJ) did Jenny burn in that time?

• 0.05 kJ
  

• 0.5 kJ
  

• 5 kJ
  

• 50 kJ

2. The Smith family is planning a hiking trip. They estimate that each person will need 2000 J of energy per hour of hiking. If they plan to hike for 4 hours, how many kilojoules (kJ) of energy do they need in total?

• 8 kJ
  

• 20 kJ
  

• 80 kJ
  

• 800 kJ

The average energy consumption of a refrigerator is 1.5 kJ per hour. If the refrigerator runs for 24 hours a day, how many joules (J) of energy does it consume in a day?

• 36 J

• 36000 J

• 0.036 J

• 16 J

The energy content of a chocolate bar is 300 kcal.

How many kilojoules (kJ) does the chocolate bar provide?

(1 kcal = 4.2 kJ)

• 1260 kJ

• 71.4 kJ

• 0.3 kJ

• 1.26 kJ

A can of soda contains 150 kJ of energy. How many kilocalorie (kcal) are in the can of soda?

(1 kcal = 4.2 kJ)

• 0.028 kcal

• 630 kcal

• 150000 kcal

• 35.7 kcal

How many minutes of cycling would Jacob need to do to burn off all the energy from 100 grams of rice?
(considering that cycling consumes 25 kJ per minute and 100 grams of rice provide 500 kJ)

• 20 minutes

• 10 minutes

• 5 minutes

• 2 minutes

Emily wants to burn off the energy from 10 grams of rice by cycling. How long does she need to cycle?
considering that cycling consumes 25 kJ per minute and 100 grams of rice provide 500 kJ.

• 20 minutes

• 10 minutes

• b) 5 minutes

• 2 minutes