Potential and Kinetic Energy Problems

1
Potential and Kinetic Energy Problems

• What is the potential energy of a rock that
  weighs 100 Newtons that is sitting on top of a
  hill 300 meters high?

2
Potential and Kinetic Energy Problems

• What is the potential energy of a rock that
  weighs 100 Newtons that is sitting on top of a
  hill 300 meters high?
• PE mgh

3
Potential and Kinetic Energy Problems

• What is the potential energy of a rock that
  weighs 100 Newtons that is sitting on top of a
  hill 300 meters high?
• PE mgh
• PE 100N x 300m

4
Potential and Kinetic Energy Problems

• What is the potential energy of a rock that
  weighs 100 Newtons that is sitting on top of a
  hill 300 meters high?
• PE mgh
• PE 100N x 300m
• PE 30,000Nm

5
Potential and Kinetic Energy Problems

• What is the potential energy of a rock that
  weighs 100 Newtons that is sitting on top of a
  hill 300 meters high?
• PE mgh
• PE 100N x 300m
• PE 30,000Nm
• PE 30,000J

6
Potential and Kinetic Energy Problems

• 2. What is the kinetic energy of a bicycle with a
  mass of 14 kg traveling at a velocity of 3 m/s?

7
Potential and Kinetic Energy Problems

• 2. What is the kinetic energy of a bicycle with a
  mass of 14 kg traveling at a velocity of 3 m/s?

KE ½ mv2
8
Potential and Kinetic Energy Problems

• 2. What is the kinetic energy of a bicycle with a
  mass of 14 kg traveling at a velocity of 3 m/s?

KE ½ mv2 KE ½ (14kg)(3m/s)2
Square 1st
9
Potential and Kinetic Energy Problems

• 2. What is the kinetic energy of a bicycle with a
  mass of 14 kg traveling at a velocity of 3 m/s?

KE ½ mv2 KE ½ (14kg)(3m/s)2 KE ½ (14kg)
(9m2/s2)
Multiply 2nd
10
Potential and Kinetic Energy Problems

• 2. What is the kinetic energy of a bicycle with a
  mass of 14 kg traveling at a velocity of 3 m/s?

KE ½ mv2 KE ½ (14kg)(3m/s)2 KE ½ (14kg)
(9m2/s2) KE ½ 126 kgm2/s2 126 Nm

11
Potential and Kinetic Energy Problems

• 2. What is the kinetic energy of a bicycle with a
  mass of 14 kg traveling at a velocity of 3 m/s?

KE ½ mv2 KE ½ (14kg)(3m/s)2 KE ½ (14kg)
(9m2/s2) KE ½ 126 kgm2/s2 126 Nm

Kgm/s2
12
Potential and Kinetic Energy Problems

• 2. What is the kinetic energy of a bicycle with a
  mass of 14 kg traveling at a velocity of 3 m/s?

KE ½ mv2 KE ½ (14kg)(3m/s)2 KE ½ (14kg)
(9m2/s2) KE ½ 126 kgm2/s2 126 Nm

Divide last
13
Potential and Kinetic Energy Problems

• 2. What is the kinetic energy of a bicycle with a
  mass of 14 kg traveling at a velocity of 3 m/s?

KE ½ mv2 KE ½ (14kg)(3m/s)2 KE ½ (14kg)
(9m2/s2) KE ½ 126 kgm2/s2 126 Nm KE 63
Joules
14
Potential and Kinetic Energy Problems

• 3. A 1-kilogram ball has a kinetic energy of 50
  joules. What is the velocity of the ball?

15
Potential and Kinetic Energy Problems

• 3. A 1-kilogram ball has a kinetic energy of 50
  joules. What is the velocity of the ball?
• KE ½ mv2

16
Potential and Kinetic Energy Problems

• 3. A 1-kilogram ball has a kinetic energy of 50
  joules. What is the velocity of the ball?
• KE ½ mv2
• 50J ½ (1kg)v2

17
Potential and Kinetic Energy Problems

• 3. A 1-kilogram ball has a kinetic energy of 50
  joules. What is the velocity of the ball?
• KE ½ mv2
• 50J ½ (1kg)v2
• 2 x 50J (1kg)v2 x 2
• 2

18
Potential and Kinetic Energy Problems

• 3. A 1-kilogram ball has a kinetic energy of 50
  joules. What is the velocity of the ball?
• KE ½ mv2
• 50J ½ (1kg)v2
• 2 x 50J (1kg)v2 x 2
• 2
• 100kgm2/s2 (1kg)v2
• 1 kg 1kg

19
Potential and Kinetic Energy Problems

• 3. A 1-kilogram ball has a kinetic energy of 50
  joules. What is the velocity of the ball?
• KE ½ mv2
• 50J ½ (1kg)v2
• 2 x 50J (1kg)v2 x 2
• 2
• 100kgm2/s2 (1kg)v2
• 1 kg 1kg

100 m2/s2 v2
20
Potential and Kinetic Energy Problems

• 3. A 1-kilogram ball has a kinetic energy of 50
  joules. What is the velocity of the ball?
• KE ½ mv2
• 50J ½ (1kg)v2
• 2 x 50J (1kg)v2 x 2
• 2
• 100kgm2/s2 (1kg)v2
• 1 kg 1kg

100 m2/s2 v2
10m/s v
21
Potential and Kinetic Energy Problems

• 4. What is the potential energy of the rock?

22
Potential and Kinetic Energy Problems

• 4. What is the potential energy of the rock?
• Given in kg, not Newtonsmust multiply mass
  times gravity

23
Potential and Kinetic Energy Problems

• 4. What is the potential energy of the rock?
• PE mgh

24
Potential and Kinetic Energy Problems

• 4. What is the potential energy of the rock?
• PE mgh
• PE 95kg(9.8m/s2)(100m)

25
Potential and Kinetic Energy Problems

• 4. What is the potential energy of the rock?
• PE mgh
• PE 95kg(9.8m/s2)(100m)
• PE 93,100 kgm2/s2 kgm/s2 N m

26
Potential and Kinetic Energy Problems

• 4. What is the potential energy of the rock?
• PE mgh
• PE 95kg(9.8m/s2)(100m)
• PE 93,100 kgm2/s2 kgm/s2 N m
• PE 93,100 Nm

27
Potential and Kinetic Energy Problems

• 4. What is the potential energy of the rock?
• PE mgh
• PE 95kg(9.8m/s2)(100m)
• PE 93,100 kgm2/s2 kgm/s2 N m
• PE 93,100 Nm
• PE 93,100 J

28
Potential and Kinetic Energy Problems

• 5. What is the approximate difference in
  gravitational potential energy of the two shaded
  boxes?

29
Potential and Kinetic Energy Problems

• 5. What is the approximate difference in
  gravitational potential energy of the two shaded
  boxes?
• PE mgh

30
Potential and Kinetic Energy Problems

• 5. What is the approximate difference in
  gravitational potential energy of the two shaded
  boxes?
• PE mgh
• PE 2.0kg(9.8m/s2)(3.0m)

31
Potential and Kinetic Energy Problems

• 5. What is the approximate difference in
  gravitational potential energy of the two shaded
  boxes?
• PE mgh
• PE 2.0kg(9.8m/s2)(3.0m)
• PE 58.8 kgm2/s2 or Nm

32
Potential and Kinetic Energy Problems

• 5. What is the approximate difference in
  gravitational potential energy of the two shaded
  boxes?
• PE mgh
• PE 2.0kg(9.8m/s2)(3.0m)
• PE 58.8 kgm2/s2 or Nm
• PE 58.8 J

33
Potential and Kinetic Energy Problems

• 5. What is the approximate difference in
  gravitational potential energy of the two shaded
  boxes?
• PE mgh

34
Potential and Kinetic Energy Problems

• 5. What is the approximate difference in
  gravitational potential energy of the two shaded
  boxes?
• PE mgh
• PE 2.0kg (9.8m/s2)(1.0m)

35
Potential and Kinetic Energy Problems

• 5. What is the approximate difference in
  gravitational potential energy of the two shaded
  boxes?
• PE mgh
• PE 2.0kg (9.8m/s2)(1.0m)
• PE 19.6 kgm/s2 or Nm

36
Potential and Kinetic Energy Problems

• 5. What is the approximate difference in
  gravitational potential energy of the two shaded
  boxes?
• PE mgh
• PE 2.0kg (9.8m/s2)(1.0m)
• PE 19.6 kgm/s2 or Nm
• PE 19.6 J

37
Potential and Kinetic Energy Problems

• 5. What is the approximate difference in
  gravitational potential energy of the two shaded
  boxes?
• 58.8J 19.6J 39.2J