1. Explain contact forces and non-contact forces giving two examples. 2. A stationary object has no forces acting on it. Is it true or false? Justify your answer. 3. State any two properties of gravitational forces? 4. A less massive object has more inertia than a more massive object. Is it true or false? Justify your answer. 5. Two brass balls of masses 2 kg and 0.5 kg experience a force of attraction of 2N. What is the force of attraction when the distance between their centers is doubled? 6. An object that is not accelerating or decelerating has zero net force acting on it. Explain. 7. An object requires the force of 100N to achieve the acceleration ‘a’. If the mass of the object is 500 kg what will be the value of ‘a’? 8. A ball is hanging by a string from the ceiling of the roof .Draw a neat labeled diagram showing the forces acting on the ball and the string? 9. Identical packets are dropped from two aeroplanes at a same time, one above the equator and the other above the North Pole, both at a height h. assuming that all conditions are identical, will those packets take same time to reach the surface of earth. Justify your answer. 10. If the radius of the earth was half of its present value and its mass 1/8th of the present mass, then the g value would have been reduced to? 11. An object of mass 2 kg is sliding with a constant velocity of 4m s-1 on a frictionless horizontal table. Then calculate the force required to keep the object moving with the same velocity? Justify your answer. 12. How do safety belts of cars help in passengers from getting hurt when there is an accident? 13. Calculate the force required to stop a car moving with a velocity of 30 m s-1 in 10seconds.the mass of the car is 1500kg. 14. A horse continues to apply a force in order to move the cart with a constant speed. Explain why? 15. What is linear momentum? What are the factors on which does it depend? 16. The mass of a goods lorry is 4000 kg and the mass of goods loaded on it is 20000 kg. If the lorry is moving with a velocity of 2m s -1 what will be its momentum? 17.A body dropped freely under gravity reaches the ground in 4s. find: a) velocity with which it strikes the ground. b) height from which it is thrown (g = 9.8 m s -2 ) 18. 1 kgf = ______________N b) 1N = ______________dyne The one who answers these questions correctly will be marked as brainliest , a thanks and I will be following you
Answers
Answer:
1) What is Non-Contact Force?
When you jump, you always return back to the surface. Why? Is there anything that is holding your feet when you try to jump? When you throw a ball high up in the air, it reaches the highest point and then it invariably return back to its thrower on the ground. These occurrences can be explained by the non-contact force.
Non-Contact Forces Types
Gravitational Force
Electrostatic Force
Examples of Non-Contact Force.
- Various Non-Contact Force examples from our daily life are provided below.
- An apple falling down from a tree is one of the best examples of non contact force.
- Iron pins attracted in the presence of a magnet bar without any physical contact.
- Falling of raindrops on earth is also an example of non-contact force.
- The charging of the hair and attraction of paper bits towards it.
- Two magnets are placed close to each other is also a non contact force example.
- Free fall of a ball towards earth is by the virtue of gravity.
- Leaves falling from a tree is an example of non-contact force.
- Electromagnetism is another example of non-contact force.
- There are various examples from electrostatics showing the attraction of small materials towards an object.
2) yes,When no net force is applied to a moving object, it still comes to rest because of its inertia. ... An object at rest will stay at rest unless acted on by an unbalanced force.
3) Gravitational force−Properties:
(1) It is a universal attractive force. It is directly proportional to the product of the masses of the two bodies.
(2) It obey inverse square law.
(3) It is the weakest force known in nature.
4) A more massive object has more inertia than a less massive object. Fast-moving objects have more inertia than slow-moving objects. An object would not have any inertia in a gravity-free environment (if there is such a place). Inertia is the tendency of all objects to resist motion and ultimately stop..
5) force between the balls= 2N
g=GmM/r²
g'=GmM/(2r)²=GmM/4r²
by equating g and g'
GmM/r²=GmM/4r²
so g=g'/4 or 4g=g'
if u got confused then in the equation just cancel out GmM/r² and u get the ratio 1:1/4
as g' is the new value of g after doubling distances, so let's substitute 2N with g as it is its value if distance is not doubled.
so 2N=4g'
g'=1/2 N
6) An object that is not accelerating or decelerating has zero net force acting on it. The only way to slow down a moving object is to apply a net force to it. When no net force is applied to a moving object, it still comes to rest because of its inertia. Objects tend to stay moving because of a force called inertia
7) Given :
Force = 100 N
Mass = 500 kg
Solution :
We know that,
F = m × a
⇒ 100 = 500 × a
⇒ a = 0.2 m/s²
8) refer at the last for more info..
9) No, those packets do not take same time to reach the surface of the earth. Because the value of g (i.e., acceleration due to gravity is) different at poles and equator due to rotation of the earth and is given by g’= g -a>2rsin0 and at poles 0 = 0 whereas at equator 0 = 90°.
Since, g is greatest at the poles than at the equator. So, packet dropped above the north pole will reach first at the surface of the earth
10) Answer:
Given:
Radius of Earth is made half.
Mass of Earth is made ⅛ of present mass.
To find:
New value of gravitational acceleration .
Calculation:
Let new gravity be g" , new radius be r" and new mass be m".
∴ g" = Gm"/(r")²
=> g" = {G (⅛m)}/(½r)²
=> g" = (4/8) [Gm/r²]
=> g" = ½ g .........[ as g = Gm/r²]
So the new gravity will become half of the present value ;
g" = ½g
11) An object of mass 2kg is sliding with a constant velocity of 4ms-1 on a frictionless horizontal table. The force required to keep the object moving with the same velocity is. ... As velocity is to be kept the same, acceleration = 0. Force, F=ma= zero.
12) It ensures you stay inside the vehicle during a car crash. It prevents you from colliding with the dashboard, steering wheel, windshield or any other components of your car. It disperses the force your body absorbs from the accident and applies that force to areas where your body is most durable.
13)Here,
initial velocity of car(u)=0ms
−1
final velocity of car (v)=30ms
−1
time(t)=10s
we know,
v=u+at
30=0+a(10)
a=3ms
−2
we know,
F=ma
=1500×3
or F=4500N
14) In order to move a cart with a constant speed, a horse continues to apply the force to overcome friction between the cart and the ground.
15)The amount of momentum that an object has is dependent upon two variables: how much stuff is moving and how fast the stuff is moving. Momentum depends upon the variables mass and velocity. In terms of an equation, the momentum of an object is equal to the mass of the object times the velocity of the object
16) momentum=4.8 m/s.
17) u=0, g=9.8, t=4
v=u+at
v= 39.2 m/s(velocity with which it strikes the ground)
v^2 +u^2 = 2as
1536.64 + 0 = 2 X 9.8 X s
s = 1536.64/19.6
s = 78.4 m
18) 1 kgf=9.80665 n
1N= 10^5 dyne..
this is the answer for the given question...
hope this is useful..
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