Use the following information to answer the questions. A boy pulls a red sled up
ID: 1440681 • Letter: U
Question
Use the following information to answer the questions. A boy pulls a red sled up a slope by pulling a rope. The slope is inclined at 20 degrees above the horizontal. The mass of the sled is 15 kilograms. The boy pulls on the rope with 200 Newtons of force, and the rope is inclined at 30 degrees above the slope (50 degrees above the horizontal). The coefficient of kinetic friction between the sled and the hill is 0.35, the coefficient of static friction is 0.45, and the boy pulls the sled a distance of 8 meters up the slope.
1.
What is the work done on the sled by the boy?
A) 1386 Joules
B) 1028 Joules
C) 173 Joules
D) 1503 Joules
E) 1600 Joules
2.
What is the work done by the normal force on the sled as it moves up the slope?
A) none of the given answers is correct
B) 1105 Joules
C) 756 Joules
D) zero
E) 1018 Joules
3.
What is the normal force of the slope on the sled?
A) 94.5 Newtons
B) 127.3 Newtons
C) 138 Newtons
D) 38 Newtons
E) zero
4.
What is the force of kinetic friction on the sled?
A) 48 Newtons
B) zero
C) none of the given answers is correct
D) 13 Newtons
E) 62 Newtons
5.
What is the work done by friction on the sled?
A) zero
B) - 106 Joules
C) 13.3 Joules
D) - 13.3 Joules
E) 106 Joules
6.
What is the work done by the force of gravity on the sled?
A) 901 Joules
B) zero
C) -588 Joues
D) 402 Joules
E) -402 Joules
F) 588 Joules
7.
What is the sum of all the work done on the sled?
A) 877 Joules
B) zero
C) 1090 Joules
D) 1682 Joules
E) 1894 Joules
8.
What happened to the kinetic energy of sled while it was being pulled up the slope?
A) It decreased.
B) It increased.
C) It cannot be determined from the information given.
D) It remained the same.
9.
If the sled was at rest when the boy started pulling it, how fast was the sled moving after the boy pulled it 8 meters up the slope?
A) none of the given answers is correct
B) 13.6 m/s
C) zero
D) 117 m/s
E) 10.8 m/s
10.
If the sled was already moving up the hill at 3 m/s when the boy started pulling it, how fast was it going after being pulled for 8 meters?
A) 16.6 m/s
B) zero
C) 13.8 m/s
D) none of the given answers is correct
E) 11.2 m/s
could you please answer the 10 parts of the question. thanks.
Explanation / Answer
the normal force = mgcos20 - Fsin30 = 138.1348 - 100 = 38.1348 N
acceleration with which the block starts moving up is a
a = (Fcos30 - mgsin20 -kinetc friction)/m
static friction = 0.45*N = 17.16 N
kinetic friction = 0.25*N = 13.3472 N
a = 173.2 - 50.27 -13.3472)/15 = 7.3 m/s^2
a) work done by the boy
W1 = Fcos30*s = 173.2*8 = 1385.6 J
b) work done by normal force = 0
c) normal force on sled = N = 38.1348 N
d) force of kiinetic friction = fk = 13.3472 N
e) work done by friction = 13.3472*8 = 106.777 J
f) work done by gravity = mgsin20*8 = 402.2157 J
g) total work done = work done by the boy - work done by friction - work done by gravity
W = 1385.6 -106.777 - 402.2157 = 876.6 J
h) Decreases
i) v = sqrt(2*a*s) = sqrrt(2*7.3*8) = 10.8 m/s
j) v = sqrt(u^2 +2*a*s) = sqrt(3^2 + 2*7.3*8) = 11.216 m/s