Phys 1 Help

Question 1

When asked to prove that the graph of two variables gives a straight line through a given y coordinate, what should you use?

Answer 1

Compare the equation linking the two variables to y = mx + c

Question 2

What are the advantages and disadvantages of using a charging plug with a lower current?

Answer 2

Charge time increases
Heating effect is lessened
Device may attempt to draw a larger current and damage the plug

Question 3

Why does speeding up a vehicle not improve fuel economy?

Answer 3

As speed increases, drag increases
A greater volume of fuel must be consumed to maintain the higher speed
Though efficiency may increase, it has no effect on fuel economy

Question 4

If a bulb is placed in parallel with an LDR in a potential divider circuit, what is required for the bulb to light?

Answer 4

The combined resistance must be greater than that of the bulb and the fixed resistor
Therefore the voltage across the bulb will be enough for the bulb to light

Question 5

As light incident on an LDR increases, what happens to the voltage across it? Therefore, what happens to the voltage over another component?

Answer 5

Resistance decreases, so voltage decreases across the LDR. This means that voltage across other components increases

Question 6

What 4 forces act on any object being pulled by a rope?

Answer 6

Contact upwards, Tension forward, Weight downwards, Friction backwards

Question 7

Explain how an object can be moved by a rope, with reference to Newton’s laws

Answer 7

There is tension in the rope, force is exerted on the rope by the object and vice versa (N3), force on object > friction, resultant force (N2), acceleration in direction of resultant, pulling force > resistance