Advertisements
Advertisements
प्रश्न
Choose one or more correct alternatives.
Which of the forces involved in dragging a heavy object on a smooth, horizontal surface, have the same magnitude?
- The horizontal applied force
- gravitational force
- reaction force in vertical direction
- force of friction
Advertisements
उत्तर
The gravitational force and the reaction force in the vertical direction have the same magnitude. Friction is not action as the horizontal surface is smooth.
APPEARS IN
संबंधित प्रश्न
What do you mean by free fall?
What do you mean by acceleration due to gravity?
A stone is allowed to fall from the top of a tower 100 m high and at the same time another stone is projected vertically upwards from the ground with a velocity of 25 m/s. Calculate when and where the two stones will meet.
A ball thrown up vertically returns to the thrower after 6 s. Find
- the velocity with which it was thrown up,
- the maximum height it reaches, and
- its position after 4 s.
When an object is dropped from a height, it accelerates and falls down. Name the force which accelerates the object.
State whether the following statement is true or false :
A falling stone also attracts the earth.
What is the usual value of the acceleration due to gravity of earth ?
Why does a sharp knife cut objects more effectively than a blunt knife ?
An object thrown vertically upwards reaches a height of 500 m. What was its initial velocity? How long will the object take to come back to the earth? Assume g = 10 m/s2
What will be the weight of a person on earth, who weighs 9N on the moon?
What would be the value of ‘g’ on the surface of the earth if its mass was twice and its radius half of what it is now?
Figure shows the velocity-time graph of a particle of mass 100 g moving in a straight line. Calculate the force acting on the particle.
(Hint : Acceleration = Slope of the v-t graph)
A force causes an acceleration of 10 m s-2 in a body of mass 500 g. What acceleration will be caused by the same force in a body of mass 5 kg?
How are g and G realated ?
State whether the below statement is True or False.
Neglecting air resistance, a body falling freely near the earth's surface has a constant acceleration.
Explain why:
Objects fall to the earth.
Write scientific reason.
The value of gravitational acceleration (g) is taken to be -g when studying the motion of an object thrown upwards in a straight line.
The mass and weight of an object on earth are 5 kg and 49 N respectively. What will be their values on the moon? Assume that the acceleration due to gravity on the moon is 1/6th of that on the earth.
Read the given passage carefully and answer the questions.
We know that the force of gravity due to the earth acts on each and every object. When we were holding the stone in our hand, the stone was experiencing this force, but it was balanced by a force that we were applying on it in the opposite direction. As a result, the stone remained at rest. Once we release the stone from our hands, the only force that acts on it is the gravitational force of the earth and the stone falls down under its influence. Whenever an object moves under the influence of the force of gravity alone, it is said to be falling freely. Thus the released stone is in a free fall. In free fall, the initial velocity of the object is zero and goes on increasing due to the acceleration due to the gravity of the earth. During free fall, the frictional force due to air opposes the motion of the object and a buoyant force also acts on the object. Thus, true free fall is possible only in a vacuum.
1) Complete the following statement by choosing the right option.
The stone held in the hand is stable because on it __.
- two unbalanced forces are exerted.
- only the gravitational force of the earth is exerted.
- gravitational force of the earth is not exerted.
- two balanced forces are exerted.
2) Why does free fall not happen on the earth?
3) Why does the velocity of the object increase during the free fall?
4) Which type of force exerts on the object during free fall?
5) Why does free fall happen only in a vacuum?
