Answer:
The force acting on the ball is 92.4 N.
Explanation:
Given that,
Initial speed of the ball, u = 0
Final speed of the ball, v = 31.6 m/s
The average power generated during the serve is 2920 W. Power generated by an object is given by :
W is the work done, W = Fd
Since,
So,
F is the force acting on the ball
So, the force acting on the ball is 92.4 N. Hence, this is the required solution.
Answer:
here we can say that acceleration of the satellite is same as the gravitational field due to Earth at that location
Explanation:
As we know that gravitational field is defined as the force experienced by the satellite per unit of mass
so we will have
now in order to find the acceleration of the satellite we know by Newton's II law
so we will have
so here we can say that acceleration of the satellite is same as the gravitational field due to Earth at that location
17.
There are three different methods for charging objects:
- Friction: in friction, two objects are rubbed against each other. As a result, electrons can be passed from one object to the other, so one object will gain a net negative charge while the other object will gain a net positive charge due to the lack of electrons.
- Conduction: this occurs when two conductive objects are put in contact with each other, and charges (electrons, usually) are transferred from one object to the other one.
- Induction: this occurs when two objects are brought closer to each other, but not in contact. If one of the two objects has a net charge (different from zero) on its surface, then it will induce a movement of charges in the second object: in particular, in the second object, charges of the opposite polarity will be attracted towards the first object, while charges of same polarity will be repelled further away.
18.
Charged objects produce around themselves an electric field. The strenght of the electric field is given by (assuming the charged objects are spherical)
where k is the Coulomb's constant, q is the magnitude of the charge and r the distance from the centre of the charge. As we see, the strength of the field is inversely proportional to the square of the distance.
Also, the direction of the field is determined by the sign of the charge:
- if the charge is positive, the electric field points away from the charge (this means that other positive charges in the field will be repelled away)
- if the charge is negative, the electric field points towards the charge (this means that other positive charges in the field will be attracted towards it)
19.
Electrical force is given by:
where k is the Coulomb's constant, q1 and q2 are the two charges, and r their separation.
Gravitational force is given by:
where G is the gravitational constant, m1 and m2 are the masses of the two objects, and r their separation.
Similarities between the two forces:
- Both are inversely proportional to the square of the distance between the two objects, r
- Both are non-contact forces (the two objects can experience the forces even if they are not in contact)
- Both forces have infinite range
Differencies between the two forces:
- The electric force can be either attractive or repulsive, while the gravitational force is attractive only
- The electric force is much stronger than the gravitational force, due to the much larger value of the Coulomb's constant k compared to the gravitational constant G