Force and Motion vol:3
This is another blog in force and Motion,we solved numerical and long answers questions from different publication. This blog is for class 10 students,who prepared for SEE examination.
We made 3 blog on force and motion chapter. If any questions missed or viewers found any mistakes then please comment on comment section.
Long Questions
1. (a). What is the difference between fall of a parachute on the moon and that on the earth?
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(b). Gravitational force produced between two bodies is 2 N when they are kept at the distance of 2 m. How much gravitational force is produced when they are kept 4 m apart?
2.(a) What happens to the weight of an object when it is taken from the earth to the moon? Why?
Ans: Weight of an object get decreased by 6 times when, we take an object from earth to the moon. This because of low acceleration due to gravity 'g' i.e 1.67 m/s^2.
(b). A stone is dropped freely from 45 m height of the tower, it reaches the ground in 3 seconds. Calculate acceleration due to gravity of the stone.
Solution,
From question,
Height of the tower (h) = 45 m
Time taken to reached ground (t) = 3 sec
Acceleration due to gravity (g) = ?
Now,
When stone is dropped from height then initial velocity (u) = 0 m/s^2
From formula,
h = ut + 1/2 gt^2
45 = o x 3 + 1/2 x g x 3^2
45 = 1/2 x 9g
45 x 2 = 9g
90 = 9g
g = 10 m/s^2
Hence, acceleration due to is 10 m/s^2
3. At what condition do a coin and a feather fall together? What is the acceleration of the feather and coin at that instant justify your answer?
Ans: A coin and a feather fall together in a vacuum, where there is no air resistance. In this condition, both objects experience the same gravitational acceleration of 9.8 m/s². Since air resistance is absent, they fall at the same rate.
This happens because, in a vacuum, the only force acting on the objects is gravity, and according to the law of universal gravitation, the acceleration due to gravity is the same for all objects.
So, even though the coin is heavier, in the absence of air resistance, both the feather and coin accelerate at the same rate, falling together.
(b). What mass of a body can a weight lifter lift on the Jupiter if s/he can lift 100 kg mass in the earth?
Earth, the weight of the object the lifter can lift is:
Weight on Earth = Mass on Earth × 𝑔 Earth
Weight on Earth=Mass on Earth×g Earth
Weight on Earth = 100 kg × 9.8m/s2
Weight on earth = 980N
This weight in newtons represents the force the lifter can exert. Now, on Jupiter, the weight of the object with the same mass will be:
Weight on Jupiter = Mass on Jupiter× 𝑔 Jupiter
Since the lifter can exert a maximum force of 980 N (the same force they can lift on Earth), we set the force on Jupiter equal to this:
Weight on Jupiter = 980
W= m x g
980 = m x 25
980/ 25 = m
m = 39.2 kg
So, the lifter can lift approximately 39. 2kg on Jupiter.
4. (a). Find out the change in gravitational force between two bodies of fixed mass, when placed at double distance.
Solution,
Let an object with mass (m1), another object whose mass is (m2) which kept at distance (d)
Now, when we made double distance
d1= 2d
then Gravitational force,
F2 = Gm1m2/d)^2
F2 = Gm1m2 / (2d)^2
F2 = Gm1m2 / 4d^2
F2 = 4 (Gm1m2/ d^2)
F2 = 1/4 F
So, the new force become 1/4 then initial ones
(b). If a large stone of 25 kg and a small stone of 5 kg dropped simultaneously from certain height,which one will reach on the ground first. Why?
For answer click here
5. (a). How would a parachute fall on the surface of the moon? Describe.
Ans: Parachute fall freely because of
1. The Moon has no atmosphere, meaning there is no air to create the air resistance that a parachute relies on to slow down its descent.
2.Without air resistance, the parachute would fall just as quickly as any other object due to the Moon's gravity.
6. Find the value of 'F' from the following figure.
7. The radius of the earth is 6400 km and the acceleration due to gravity is 9.8 m/s^2. Calculate the value of acceleration due to gravity at the height of 10 km from the surface of the earth.
Solution,
Radius of the earth= 6400 km
acceleration due to gravity 'g' = 9.8 m/s^2
height (h) = 10 km
Now,
First find mass of earth
Now finding acceleration due to gravity,
For more answers click here
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