Chapter 24:Laws of Motion

Example 24.1, Page no.484

In [1]:
#Variable declaration
m=100   #mass of body in kg
a=3.5   #acceleration in m/s**2

#calculation
F=m*a

#Result
print"F=",int(F),"N"

F= 350 N

Example 24.2, Page no.485

In [8]:
#variable declaration
m=50      #mass of body in kg
g_e=9.8   #acceleration due to gravity on earth in m/s**2
g_m=1.7   #acceleration due to gravity on moon in m/s**2
g_s=270.0 #acceleration due to gravity on sun in m/s**2

#calculation
F_1=m*g_e
F_2=m*g_m
F_3=(m*g_s)

#Result
print"Weight of the body on the earth, F_1=",int(F_1),"N"
print"Weight of the body on the moon, F_2=",int(F_2),"N"
print"Weight of the body on the sun, F_3=",round(F_3/1000,1),"kN"

Weight of the body on the earth, F_1= 490 N
Weight of the body on the moon, F_2= 85 N
Weight of the body on the sun, F_3= 13.5 kN

Example 24.3, Page no.485

In [9]:
#variable declaration
m=7.5  #mass of the body in kg
u=1.2  #velocity in m/s
F=15   #Force in N
t=2    #time in s

#calculation
a=F/m
v=u+(a*t)

#Result
print"Velocity of the body after 2 seconds, v=",round(v,1),"m/s"

Velocity of the body after 2 seconds, v= 5.2 m/s

Example 24.4, Page no.485

In [13]:
#variable declaration
m=500.0  #mass of vehicle in kg
u=25.0   #initial velocity in m/s
F=200.0  #Force in N
t=120.0  #time in s

#calculation
a=F/m
v_1=u+(a*t)
v_2=u+(-a*t)  #Force acts in the opposite direction of motion

#Result
print"Velocity of vehicle when the force acts in the dirction of motion,v_1=",int(v_1),"m/s"
print"Velocity of vehicle when the force acts in the opposite dirction of motion,v_2=",int(v_2),"m/s"

Velocity of vehicle when the force acts in the dirction of motion,v_1= 73 m/s
Velocity of vehicle when the force acts in the opposite dirction of motion,v_2= -23 m/s

Example 24.5, Page no.486

In [15]:
#variable declaration
F=50.0  #Retarding force in N
m=20.0  #mass of the body in kg
u=15    #initial velocity in m/s
v=0     #final velocity

#calculation
a=F/m
t=u/a 

#Result
print"t=",int(t),"s"

t= 6 s

Example 24.6, Page no.486

In [16]:
#variable declaration
m=2.5   #mass of the car in t
F=1     #Propelling force in N
u=10    #initial velocity in m/s
v=15    #final velocity in m/s

#calculation
a=F/m
t=(v-u)/a

#Result
print"t=",round(t,1),"s"

t= 12.5 s

Example 24.7, Page no.486

In [17]:
#variable declaration
m=800.0       #mass of electric train in t
Resistance=80 #Resistance to motion in kN
Tractive=200  #Tractive force in kN
v=25          #final velocity in m/s
u=0           #initial velocity

#calculation
F=Tractive-Resistance
a=F/m
t=(v-u)/a

#Result
print"t=",round(t,1),"s"

t= 166.7 s

Example 24.11, Page no.490

In [18]:
#variable declaration
m=50   #mass of the body in kg
a=1.2  #acceleration in m/s**2
g=9.8  #gravity in m/s**2

#calculation
F=m*(g+a)

#result
print"F=",int(F),"N"

F= 550 N

Example 24.12, Page no.490

In [19]:
#variable declaration
m=100  #mass of the body in kg
a=-0.8 #acceleration in m/s**2
g=9.8  #gravity in m/s**2

#calculation
F_1=m*(g+a)
F_2=m*(g-a)

#Result
print"(a)The lift is moving upwards, F_1=",int(F_1),"N"
print"(b)The lift is moving downwards, F_2=",int(F_2),"N"

(a)The lift is moving upwards, F_1= 900 N
(b)The lift is moving downwards, F_2= 1060 N

Example 24.13, Page no.490

In [21]:
#variable declaration
m=65.0   #mass of the body in kg
F=800.0  #Force in N
g=9.8    #gravity in m/s**2

#calculation
a=(F/m)-g

#Result
print"Acceleration of the elevator, a=",round(a,1),"m/s**2"

Acceleration of the elevator, a= 2.5 m/s**2

Example 24.14, Page no.490

In [22]:
#variable declaration
m_1=500 #mass of the elevator in kg
a=3     #acceleration in m/s**2
m_2=70  #mass of operator in kg

#calculation
R_1=m_2*(g+a)
R_2=(m_1+m_2)*(g+a)

#Result
print"Scale Reading,R_1=",int(R_1),"N"
print"Total tension in the cable of the elevator, R_2=",int(R_2),"N"

Scale Reading,R_1= 896 N
Total tension in the cable of the elevator, R_2= 7296 N

Example 24.18, Page no.495

In [23]:
#variable declaration
M=25    #mass of the machine gun in kg
m=0.03  #mass of the bullet in kg
v=250   #velocity of firing in m/s

#calculation
V=(m*v)/M

#Result
print"Velocity with which the machine gun will recoil, v=",round(V,1),"m/s"

Velocity with which the machine gun will recoil, v= 0.3 m/s
In [ ]: