15 questions
A truck travels at a speed of 80.0 km/h and has a mass of 2 000 kg. What is its kinetic energy?
22.2 kJ
494 kJ
6400 kJ
42
A quarterback throws a football weighing 315 g at a speed of 15.0 km/h and a height of 7.0 m. What is the football’s mechanical energy?
42
2.8 J
24 J
2 200 J
A Honda Fit weighing 5 600 kg has 72 000 J of kinetic energy. What speed it is travelling at?
5.1 m/s
42
26 m/s
28 000 m/s
A gorilla travels at a speed of 85 m/s with a kinetic energy of 500 kJ. What is the gorilla’s mass?
12 000 kg
42
0.138 kg
138 kg
Thor’s hammer weighs 12.0 kg. Just before he throws it, he raises it 3.00 m above the ground. What is its potential energy?
353 J
54 J
42
600 J
A big dog, named Fluffy, is raised 2.00 m off the ground by her loving human. Fluffy now has a potential energy of 8.00 kJ. What is her mass?
408 kg
157 000 kg
42
0.408 kg
A monkey on a branch weighs 20 kg and has a potential energy of 13 000 J. How far is the branch off of the ground?
66 m
2 600 000 m
130 m
42
A trapeze swings a gymnast, who weighs 75.0 kg, to a height of 9.00 m above ground at a speed of 28.0 km/h. What is the gymnast’s mechanical energy?
42
36 000 J
2 300 J
8 890 J
How much energy is needed to heat enough water to make a cup (250 mL) of hot chocolate, if the water is initially at 17.0 °C and you want to increase the temperature to 99.0 °C?
(Assume that 1.00 mL of water has a mass of 1.00 g.)
104 000 J
86 000 J
18 000 J
42
As the cup of hot chocolate in question 9 cools (1 cup = 250 mL; 1.00 mL = 1.00 g), it transitions from 99.0 °C to 77.0 °C. How much heat energy is lost in this process?
23 000 J of heat are lost
42
81 000 J of heat are lost
104 000 J of heat are lost
If 50.0 kJ of energy is used to heat 350 g of water, what is the temperature change of the water?
42
0.034 0C
34 0C
34 000 0C
A 1.80 kg block of ice, at −28.0 °C, is warmed by 65.0 kJ of energy. What is the final temperature of the ice?
18 000 0C
18 0C
-9.9 0C
42
If 115.0 g of a substance releases 67 kJ of energy as it cools from 16.0 °C to –20.0 °C, what is the specific heat capacity of the substance?
0.016 J/g0C
16 J/g0C
42
150 J/g0C
Calculate the efficiency of a sailor if she puts 900 J of work on her sails whereas the sails give out 190 J of useful work.
42
20%
400%
0.2%
A heat engine gives out 400 J of heat energy as useful work. Calculate the energy given to it as input if its efficiency is 35%.
14 000 J
9 J
42
1 100 J