NCTB Class 6 Science Chapter 11 “Force and Simple Machine” Solution:
Bangladesh Board Class 6 Science Solution Chapter 11 Force and Simple Machine Solution Exercises Question and Answer by Experienced Teacher.
NCTB Solution Class 6 Chapter 11 “Force and Simple Machine”:
|Board||NCTB Bangladesh Board|
|Chapter Name||Force and Simple Machine|
Chapter 11 “Force and Simple Machine”
Fill in the blanks
(1) When force is applied on an object, it changes or tries to change an object at rest to—— and an in motion to.
(2) Applying—– force—- work can be done by a simple machine.
(3) The position of ——in a class-I level is in the middle of applied force and load.
Ans:- The pivot.
(4) Jack screw flows the principle of —-and—–at the same time.
Ans:- lever, inclined plane.
Multiple Choice Questions:-
(1) Which one is a lever of class-II.
Ans:- (d) Nut-cracker.
(2) How is the mechanical efficiency availed from inclined plane?
Ans:- (a) Increasing length.
Answer question no.3 and 4 using the figure below.
(3) What is the mechanical efficiency of the machine shown in the figure?
Ans:- (a) 5 (5/10=5)
(4) If the length of the load-arm is increased is increased by 15cm. The mechanical efficiency—
Ans:- (a) i. Will decrease (50/25 = 2)
Short Answer Question:
(a) Ans:- Due to application of force on a body –
(i) A body changes its state from rest to motion and motion to rest.
(ii) The speed of a body in motion can be increased or decreased.
(iii) The direction of the motion of a body is changed.
(iv) The size, shape or volume of a body are changed.
(b) Ans:-All the time of cutting something by scissors it will be much easier to cut the thing placing closer to the pivot. Basically, in this case the mechanical efficiency is increased by trying to decrease the length of the load arm.
(c) Ans:- Jack-screw follows the principle of lever and inclined plane at the same time. Mechanical advantage can be availed by increasing the length of the inclined plane. On other hand, the direction of force and the direction of load are opposite. So by increasing force as well as changing direction of force jack-screw makes a work easier.
(d) Ans:- Long handled screw driver is more advantageous.
(1) (a) Ans:- The point at which the supporting body resists the strong bar to freely ascent and decent or to rotate is the pivot.
(1) (b) Ans:- The simple machines can make works easier in one or more than one way—-
(i) Multiplying the applied force by many times.
(ii) Performing a work applying less force.
(iii) Applying force in one advantageous direction.
(iv)Performing work in a particular way.
(1) (c) Ans:- We know, mechanical =
We know efficiency
Therefore, The length of inclined plane = The height of inclined plane X mechanical efficiency.
= 5×6 = 30meter.
(1) (d) Ans:- The advantages of the technique applying by the man t left the drum are- (i) It requires a small amount of force.
(2) (a) Ans:- Lever is a simple machine in which a strong bar can freely move upward and download or rotate on a supporter.
(2) (b) Ans:- The mechanical efficiency of class – III lever can be increased by increasing the length of the force are and decreasing the length of load arm.
(2) (c) Ans:- The fundamental principle of stapler: as stapler is a class – III lever, so we have to apply the force in the middle of the load and pivot to Stapple multiple sheets of paper on a plane surface.
(2) (d) Ans:- Shilpi should change the way of working in order to make the work much easier. Because, if we apply the pressure on the front portion of the stapler the it requires a small amount of force and our work will be much easier.