The answer is c or b u choose
Answer:
The change in current at
is 
Explanation:
From the question we are told that
The resistance is 
The current is 
The change in voltage with respect to time is 
The change in resistance with time is 
According to ohm's law

differentiating with respect to time using chain rule

substituting value at R = 456


The force of static friction acting on the boy is 333 Newtons.
Hence, option (d) 333N is the correct answer.
Given the data in the question;
- Weight of boy;

- Coefficient of static friction;

Force of static friction acting on the boy; 
<h3>Friction</h3>
Friction is simply referred as the resistance an object experience when moving or trying to move over another object. It can either by dynamic or static.
Static friction is the resistance experienced by a body at rest.
Coefficient of friction is the measure of how easily a body moves in relation to the other.
Static friction is expressed as;

Where
is the normal force and
is the coefficient of static friction.
We substitute our given values into the equation above

The force of static friction acting on the boy is 333 Newtons.
Hence, option (d) 333N is the correct answer.
Learn more friction: brainly.com/question/17237604
Answer:
a) < 3 , -4 >
b) < 3 , -4 >
Explanation:
a) If you can imagine this, adding vectors is like putting them "tip to tail", where you put the beginning point of vector B to the end point of vector A (or vice versa). Your new vector (A+B) would be from the "tip" of vector A to the "tail" of vector B.
Mathematically, this is the same as adding the x-components of each vector together as well as the y-components.
Vector A: 3 units along the positive x-axis: < 3 , 0 >
Vector B: 4 units along the negative y-axis: < 0 , -4 >
A+B = < 3 , 0 > + < 0 , -4 > = < (3+0) , (0+(-4)) > = < 3 , -4 >
b) Subtracting is like adding a negative, so you could use the same "tip to tail" visual by adding the negative of vector B instead (which is B in the opposite direction).
Vector A: < 3 , 0 >
Vector B: < 0 , -4 >
Vector -B: < 0 , 4 >
A-B = A+(-B) = < 3 , 0 > + < 0 , 4 > = < (3+0) , (0+4) > = < 3 , 4 >