The viscous force on an object moving through air is proportional to its velocity.
The only forces acting on an object when falling are air resistance and its weight itself. The weight acts vertically downwards whereas air resistance acts vertically upward.
Let F be the viscous force due to air molecules, B be buoyant force due to air and W be the weight of falling object. Initially, the velocity of falling object and hence the viscous force F is zero and the object is accelerated due to force
(W-B). Because of the acceleration the velocity increases and accordingly the viscous force also increases. At a certain instant, the viscous force becomes equal to W-B. The net force then becomes zero and the object falls with constant velocity. This constant velocity is called terminal velocity.
Thus at terminal velocity, air resistance and force of gravity becomes equal.
Answer:
Objects with mass exert forces on each other via the force of gravity. This force is proportional to the mass of the two interacting objects, and is inversely proportional to the square of the distance between them. The factors G, M, and r are the same for all masses at the surface of the Earth.
Answer:
Points downward, and its magnitude is 9.8 m/s^2
Explanation:
The motion of a projectile consists of two independent motions:
- A uniform horizontal motion, with constant velocity and zero acceleration. In fact, there are no forces acting on the projectile along the horizontal direction (if we neglect air resistance), so the acceleration along this direction is zero.
- A vertical motion, with constant acceleration g = 9.8 m/s^2 towards the ground (downward), due to the presence of gravity wich "pulls" the projectile downward.
The total acceleration of the projectile is given by the resultant of the horizontal and vertical components of the acceleration. But we said that the horizontal component is zero, therefore the total acceleration corresponds just to its vertical component, therefore it is a vector with magnitude 9.8 m/s^2 which points downward.
Correct matching:
1 acceleration -->
rate of change in velocity, which is the change in velocity divided by the change in time
2. speed --> the rate at which an object changes position when traveling in a certain direction
4. gravity --> force of attraction between all masses in the universe
5. Inertia --> an object´s resistance to a change in motion
3. friction --> force of resistance acting between objects in contact and tending to dampen their motion
6. velocity --> the rate at which an object changes position
I really don’t know but I think it’s D
