Question #60c57
4 Answers
Q.7. Locomotive requires to exert constant force of
Force required to be exerted
Additional force is required to accelerate the train. We know that rate of change of speed is acceleration. Using Newton's Second Law of motion and inserting values in SI units we get
#F=ma#
#F=30000xx0.5=15000N#
Total force required
#17.04kN#
Q. 8. We know that
#"Power" ="work done"/"time taken"# ......(1)
Work done
#W="Force"xx"Distance"# .....(2)
Also
#"Force"=mg# ......(3)
where#m# is mass of object and#g# is acceleration due to gravity,#=9.8ms^-2#
Inserting values in equation (1) in SI units we get
#"Power" =(30000xx9.8xx24)/(0.5xx60xx60)#
#"Power" =7056000/1800=3920W#
#3.92kW#
Q. 9. Centrifugal force
#F_c=mromega^2# ......(1)
It is given that mass revolves about a point 2 meters from its centre of gravity.
Units of
Mass revolves at a speed of 60 revolutions per minute.
One revolution is equal to
Hence
Inserting values in (1) we get
#F_c=5xx2xx(2pi)^2#
#=>F_c=394.8N# , rounded to one decimal place.