Answer:
Positive work
Explanation:
When work and the exerted force are in the same direction, then the work done is positive.
In the question, we understand that Marvin lifts a box up (i.e. over his head). The force to lift the box acts in the upward direction and the work done itself is also in the upward direction (from the floor to Marvin's head).
Since these two are in the same direction, then we can conclude that the work done is positive.
The work done on the box by the applied force is zero.
The work done by the force of gravity is 75.95 J
The work done on the box by the normal force is 75.95 J.
<h3>The given parameters:</h3>
- Mass of the box, m = 3.1 kg
- Distance moved by the box, d = 2.5 m
- Coefficient of friction, = 0.35
- Inclination of the force, θ = 30⁰
<h3>What is work - done?</h3>
- Work is said to be done when the applied force moves an object to a certain distance
The work done on the box by the applied force is calculated as;
where;
a is the acceleration of the box
The acceleration of the box is zero since the box moved at a constant speed.
The work done by the force of gravity is calculated as follows;
The work done on the box by the normal force is calculated as follows;
Learn more about work done here: brainly.com/question/8119756
Answer:
(a) Negative Q
(b) Positive Q
Explanation:
Charge is the inherent property of matter due to the transference of electrons.
There are three methods of charging a body.
(i) Charging by friction: When two uncharged bodies rubbed together, then one body gets positive charged and the other is negatively charges it is due to the transference of electrons form one body to another.
(ii) Conduction: when a charged body comes in contact with the another uncharged body, the uncharged body gets the same charge and the charge is distributed equally.
(iii) Induction: When a uncharged body keep near the charged body, the uncharged body gets the same amount of charge but opposite in sign.
(a) When a small tack of charge Q is lowered into the hole, then due to the process of induction, the charge on the inner surface of the shell is - Q.
(b) Due to the process of conduction, the charge on the outer surface of the shell is Q.
The benefits of stretching the lower back on a regular basis include improving the range of motion,reducing back pain , and increasing the flexibility of tendons
Answer:
20m/s
Explanation:
Given parameters:
Displacement = 200m
Time = 10s
Unknown:
Velocity of Usain Bolt = ?
Solution:
The velocity of a body is the displacement divided by the time taken.
Therefore
Velocity = 
So;
Velocity = 
= 20m/s
