Work
Someone pushes a textbook across a desk. They push it 0.4 m and use a force of 5.2 N. How much work did they do on the book?
W = F * d
W = 5.2 * 0.4
W = 2.16 J
A 1200 kg car is traveling at 17 m/s. What is the car's kinetic energy?
KE = 1/2 * m * v2
KE = 1/2 * 1200 * 172
KE = 173,400 J
Calculate the GPE of a pencil resting on a table, if the pencil has a mass of 0.03 kg and the table's height is 0.7 m
GPE = m * g * h
GPE = 0.03 * 9.8 * 0.7
GPE = 0.2058 J
A falling apple has a GPE of 7.5 J and a KE of 2.4 J. What is its TME?
7.5 + 2.4
9.9 J
What is Ms. Cory's first name?
To get this right, you must have the correct spelling!
Eleanor
An athlete lifts a weight 0.8 m into the air. The weight has a mass of 100 kg. How much work did the athlete do on the weight?
Fg = m * g
Fg = 100 * 9.8
Fg = 980 N
W = F * d
W = 980 * 0.8
W = 784 J
A canoe has 170 J of kinetic energy, until someone pushes on it. The push causes the boat to speed up, and now it has 250 J of kinetic energy. How much work did the person do on the boat?
W = KEf - KEi
W = 250 - 170
W = 80 J
A coconut falls out of a tree. It starts at a height of 11 m and ends up on the ground. The coconut has a mass of 2.1 kg.
What is the GPE of the coconut once it's on the ground?
A sled is in a closed system. Its TME at the top of a hill is 1800 J. What will be its TME at the bottom of the hill? How do you know?
1800 J
It is unchanged because the sled is in a closed system (meaning TME cannot change).
Where did Ms. Cory study abroad in college?
Korea (Seoul)
A student is flying a kite. The kite has a mass of 0.07 kg. She pulls on the kits, causing the kite to speed up from 0.9 m/s to 1.6 m/s. How much work did she do on the kite?
W = 1/2 * m * vf2 - 1/2 * m * vi2
W = 1/2 * 0.07 * 1.62 - 1/2 * 0.07 * 0.92
W = 0.06125 J
The moon has a mass of 7.35 * 1022 kg. It is moving at a velocity of about 3.683 * 106 m/s. What is the kinetic energy of the moon?
KE = 1/2 * m * v2
KE = 1/2 * 7.35 E 22 * (3.683 E 6)2
KE = 4.98 E 35
KE = 4.98 * 1035 J
A dolphin jumps into the air. At its peak, it has 1225 J of GPE. If the dolphin's mass is 50 kg, what height did the dolphin jump to?
GPE = m * g * h
1225 = 50 * 9.8 * h
1225 = 490 * h
2.5 m = h
A ball is rolling down a hill in a closed system. At the top of the hill, its TME is 42 J. As it rolls, friction and air resistance do -18 J of work on the ball.
What will be the ball's TME at the bottom of the hill?
TMEi + Wext = TMEf
42 + -18 = TMEf
24 J = TMEf
How old is Ms. Cory?
Whichever group gets the closest gets the point.
31
A pencil is rolling across a desk in an open system. The pencil starts with 7.1 J of TME, and ends with 0 J of TME. How much work did friction and air resistance do on the pencil?
Wext = TMEf - TMEi
Wext = 0 - 7.1
Wext = -7.1 J
What is the velocity of a tennis ball that has a kinetic energy of 42 J and a mass of 0.8 kg?
KE = 1/2 * m * v2
42 = 1/2 * 0.8 * v2
42 = 0.4 * v2
105 = v2
10.25 m/s = v
A soccer player kicks a soccer ball into the air in a closed system. The ball starts on the ground, where it has 68 J of kinetic energy from the kick.
When the ball reaches its peak in the air, its kinetic energy is 0. What is the ball's GPE at this peak?
TME = GPE + KE
TMEi = 0 + 68
TMEi = 68 J
IN a closed system, TMEi = TMEf so:
TMEf = 68 J
TME = GPE + KE
68 = GPE + 0
68 J = GPE
What is the TME of a 6.8 kg bird that is flying at a velocity of 3.1 m/s at a height of 30 m?
KE = 1/2 * m * v2
KE = 1/2 * 6.8 * 3.12
KE = 32.674
GPE = m * g * h
GPE = 6.8 * 9.8 * 30
GPE = 1911
TME = GPE + KE
TME = 1911 + 32.674
TME = 1943.674 J
When did Ms. Cory get married? (say the month and year)
July 2025
A ball is falling. When it starts, it has 45 J of TME. When it hits the ground, it is traveling at a velocity of 4 m/s. The ball has a mass of 2.5 kg.
How much work did air resistance do on the ball while it was falling?
GPEf = 0 J (on the ground)
KEf = 1/2 * 2.5 * 42
KEf = 20 J
TMEf = GPEf + KEf
TMEf = 0 + 20
TMEf = 20 J
TMEi + Wext = TMEf
45 + Wext = 20
Wext = -25 J
A 75 kg skater is in a closed system. She starts at the top of a ramp (h=9 m) from rest. What will be her total mechanical energy at the bottom of the ramp?
TMEi = GPEi + KEi
GPEi = m * g * h
GPEi = 75 * 9.8 * 9
GPEi = 6615 J
KEi = 0 (skater starts from rest)
TMEi = 6615 + 0
TMEi = 6615
In a closed system, TMEi = TMEf
TMEf = 6615 J
What did Ms. Cory major in in college?
Chemistry