In a classroom demonstration, a 82.4 kg physics professor lies on a bed of nails
ID: 1324313 • Letter: I
Question
In a classroom demonstration, a 82.4 kg physics professor lies on a bed of nails. The bed consists of a large number of evenly spaced, relatively sharp nails mounted in a board so that the points extend vertically outward from the board. While the professor is lying down, approximately 1,750 nails make contact with his body.
If the area of contact at the head of each nail is 1.18 106 m2, what is the average pressure at each contact?
Question options:
3.99 104 Pa
3.91 105 Pa
2.56 106 Pa
2.51 107 Pa
2.11 108 Pa
A 2.40 kg block displaces 10.0 kg of water when it is held fully immersed. The object is then tied down as shown in the figure; and it displaces 4.60 kg of water. What is the tension in the string?
Question 10 options:
16.4 N
21.6 N
23.5 N
32.7 N
45.1 N
A)3.99 104 Pa
B)3.91 105 Pa
C)2.56 106 Pa
D)2.51 107 Pa
E)2.11 108 Pa
In a classroom demonstration, a 82.4 kg physics professor lies on a ½bed of nails.½ The bed consists of a large number of evenly spaced, relatively sharp nails mounted in a board so that the points extend vertically outward from the board. While the professor is lying down, approximately 1,750 nails make contact with his body. If the area of contact at the head of each nail is 1.18 ½ 10½6 m2, what is the average pressure at each contact? Question options: A) 3.99 ½ 104 Pa B) 3.91 ½ 105 Pa C) 2.56 ½ 106 Pa D) 2.51 ½ 107 Pa E) 2.11 ½ 108 Pa A 2.40 kg block displaces 10.0 kg of water when it is held fully immersed. The object is then tied down as shown in the figure; and it displaces 4.60 kg of water. What is the tension in the string? Question 10 options: A) 16.4 N B) 21.6 N C) 23.5 N D) 32.7 N E) 45.1 NExplanation / Answer
Here , as Force = mg
Pressure = Force / area
Pressure = 82.4 *9.8/(1750*1.18*10^-6)
Pressure = 3.91 *10^5 Pa
the pressure at the head is 3.91 *10^5 Pa
A)
let the tension in the string is T
4.6 g - T = 2.40g
T = 2.2 * 9.8
T = 21.6 N
the tension in the string is 21.6 N