Ch 5 Whal accewralion of a 304t N ea down a Question 7 caloutate the magnitude o
ID: 1641045 • Letter: C
Question
Explanation / Answer
6)Weight of car = 3041 N
Mass of car = 3041/9.8 = 310.3 kg
Slope of incline =12o
Coefficient of kinetic friction = n=0.12
net force acting on the car = mgsin12o-nmgcos12o = 3041xsin12o - 0.12x3041cos12o = 275.3 N
acceleration = 275.3/310.3 = 0.887 m/s2 downwards along the slope
(Note : acceleration is basically equal to gsin12o-ngcos12o and is independent of mass or weight of car)
7)Since the body is moving up the slope, the friction force is also acting downwards along the slope
Coeffieicient of friction =n= 0.11
Total acceleration = gsin18o + ngcos18o = 4.09m/s2 downwards along the slope
8)This is similar to question 6
coffiicient of fricition = n=0.11
Acceleration = gsin12o-ngcos12o =0.1 m/s2 downwards along the slope
9)Coefficient of kinetic friction = n=0.24
Minimum force needed to insert piston into cylinder = 334Newton
Let normal force be Nf
nNf = 334
Nf = 334/0.24 = 1391.67 Newtons
10)Total compressive force on antenna = (60+431)x9.8 = 4811.8N
Area of cross section of antenna = pix0.132 =0.053m2
Compressive stress = 4811.8/0.053 = 90788.7 N/m2
Young's Modulus = 2.1x1011 N/m2
By Hooke's Law, Compressive strain = 90788.7/2.1x1011 = 4.32x10-7
height of antenna = 544m
Compression in antenna = 544* 4.32x10-7 = 2.35x10-4 m = 0.235mm
11) Mass of ship = 1014kg
Acceleration = 27km/s2 = 27000m/s2
Per newton's second law, F =ma = 1014*27000 = 27378000N = 27.378 million Newtons
12) Force = 64.7N
mass = 5.91kg
Per Newton's Second Law, F=ma
a = F/m = 64.7/5.91 = 10.95m/s2