1. Here, we’ll review the formula to find pressure and use it for an example calculation

2. Remember, the formula for Pressure is The formula for pressure is:

3. Pressure is equal to force divided by area The formula for pressure is: Pressure = Force Area

4. Or P is equal to F divided by A The formula for pressure is: P = F A Pressure = Force Area

5. Where P stands for the pressure, usually measured in Pascals The formula for pressure is: P = F A Pressure measured in Pascals (Pa)

6. F stands for force, measured in Newtons The formula for pressure is: P = F A Pressure measured in Pascals (Pa) Force measured in Newtons (N)

7. And A stands for area, usually measured in square meters. The formula for pressure is: P = F A Pressure measured in Pascals (Pa) Force measured in Newtons (N) Area measured in square meters (m 2 )

8. The sole of a boot has a total area of 0.028 m 2. A 55.1 kg person is wearing these boots and takes a step on one foot. a)Calculate the weight of the person. b)Calculate the pressure the boot is applying to the ground. Let’s do an example question. The sole of a boot has a total area of 0.028 square meters.

9. The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. a)Calculate the weight of the person. b)Calculate the pressure the boot is applying to the ground. A 55 kg person is wearing these boots and is stepping so that all her weight is temporarily on one foot.

10. The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. a)Calculate the weight of the person. b)Calculate the pressure the boot is applying to the ground. The (a) part of this question asks us to calculate this person’s weight, which is the force of gravity acting on her.

11. And the b part of this question asks us to calculate the pressure the boot is applying to the ground as the person takes a step on one foot. The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. a)Calculate the weight of the person. b)Calculate the pressure the boot is applying to the ground.

12. We’ll start by answering the (a) part. We need to calculate the weight of the person wearing the boots. The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. a) Calculate the weight of the person.

13. The formula we use to calculate weight from mass is W = m times g, The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. a) Calculate the weight of the person. = × W m g

14. Where “w” is the weight, or force of gravity, in Newtons The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. a) Calculate the weight of the person. Weight in Newtons (N) = × W m g

15. m is the mass in kilograms The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. a) Calculate the weight of the person. Mass in Kilograms (kg) = × W m g Weight in Newtons (N)

16. And g is the acceleration of gravity in Newtons per kilogram. The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. a) Calculate the weight of the person. Acceleration of Gravity (N/kg) = × W m g Mass in Kilograms (kg) Weight in Newtons (N)

17. We can substitute 55 kg in for the mass of the person. The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. a) Calculate the weight of the person. = × W m g = W 55 kg

18. And we know that the acceleration of gravity on Earth, g, is 9.8 Newtons per kilogram The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. a) Calculate the weight of the person. = × W m g = × W 55 kg 9.8 N kg

19. Multiplying 55 and 9.8, gives us 539. The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. a) Calculate the weight of the person. = × W m g = × W 55 kg 9.8 N kg = W 539 N

20. The unit kilograms can be cancelled out The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. a) Calculate the weight of the person. = × W m g = × W 55 kg 9.8 N kg = W 539 N

21. Leaving us with Newtons as the unit for our answer. The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. a) Calculate the weight of the person. = × W m g = × W 55 kg 9.8 N kg = W 539 N

22. So now we have the answer for the a) part of the question. The weight, or force of gravity on the person is 539 N The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. a) Calculate the weight of the person. = × W m g = × W 55 kg 9.8 N kg = W 539 N

23. We’ll make a note up here that the weight of the person is 539 Newtons. The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. a) Calculate the weight of the person. = × W m g = × W 55 kg 9.8 N kg = W 539 N = W

24. Weight is the same as the force of gravity acting on a person, (click) so we can replace the letter W with the letter F, for force The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. a) Calculate the weight of the person. = W 539 N Weight is the same as the Force of Gravity F

25. F And state that the force of gravity acting on the person is 539 Newtons The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. a) Calculate the weight of the person. = 539 N Force of Gravity

26. F Part b of this question asks us to calculate the pressure the boot is applying to the ground as the person is taking a step on one foot. The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. b) Calculate the pressure the boot is applying to the ground. = 539 N

27. F Remember, the formula for pressure is Pressure in pascals is equal to force in Newtons divided by area in square meters. The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. b) Calculate the pressure the boot is applying to the ground. = 539 N P = F A Pressure measured in Pascals (Pa) Force measured in Newtons (N) Area measured in square meters (m 2 )

28. F When the person is taking a step on one foot, all of her weight is resting on one foot, The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. b) Calculate the pressure the boot is applying to the ground. = 539 N P = F A = 0.028 m 2 539 N

29. F So we can substitute 539 Newtons in for the force the boot is applying to the ground. The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. b) Calculate the pressure the boot is applying to the ground. = 539 N P = F A = 0.028 m 2

30. And we’ll substitute 0.028 square meters for the area of the boot through which the force is being applied The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. b) Calculate the pressure the boot is applying to the ground. P = F A = 539 N 0.028 m 2

31. 19 250 N/m 2 N/m 2 539 Newtons divided by 0.028 square meters comes out to 19 250 Newtons per square meter. The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. b) Calculate the pressure the boot is applying to the ground. P = F A = 539 N 0.028 m 2 =

32. The unit Newtons per square meter is the same a 1 pascal The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. b) Calculate the pressure the boot is applying to the ground. P = F A = 539 N 0.028 m 2 =19 250 N/m 2 The same as Pascals (Pa) N/m 2

33. So we can replace Newtons per square meter with pascals. The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. b) Calculate the pressure the boot is applying to the ground. P = F A = 539 N 0.028 m 2 =19 250 N/m 2 The same as Pascals (Pa) N/m 2 Pa

34. So the answer is, the pressure the boot is applying to the ground is 19 250 Pascals. The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. b) Calculate the pressure the boot is applying to the ground. P = F A = 539 N 0.028 m 2 =19 250 N/m 2 Pa P

35. Dividing Pascals by 1000, gives us the pressure in kilopascals The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. b) Calculate the pressure the boot is applying to the ground. P = F A = 539 N 0.028 m 2 =19 250 N/m 2 Pa = ÷1000 19.25 N/m 2 kPa

36. Which comes out to 19.25 kilopascals. The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. b) Calculate the pressure the boot is applying to the ground. P = F A = 539 N 0.028 m 2 =19 250 N/m 2 Pa = ÷1000 19.25 N/m 2 kPa

37. So the final answer could be stated as, the pressure is 19 250 Pascals or 19.25 kilopascals. The sole of a boot has a total area of 0.028 m 2. A 55 kg person is wearing these boots and takes a step on one foot. b) Calculate the pressure the boot is applying to the ground. P = F A = 539 N 0.028 m 2 =19 250 N/m 2 Pa = 19.25 N/m 2 kPa P P