physics Flashcards
(23 cards)
which direction does the arrow for normal contact force go
up
the drag lift pulls the skier with a constant resultant force of 300N for a distance of 45m
calculate the work done to pull the skier up the slop
work done = force x distance
300 x 45 = 13500
when the glider is released ___________ energy stored in the rubber band decreases and the glider gains ________ energy
- elastic potential
- kinetic
on a plane what force acts on it pulling it down
weight
how can you tell the limit of proportionality in a spring has not been exceeded
the extension is directly proportional to the force applied
calculate the swing content when the extension is 0.4 and the force is 160
F = ke
k = F/e
= 160/0.4
= 400 n/m
Each time the student does one chin-up he lifts his body 0.40 m vertically upwards.The mass of the student is 65 kg.The student is able to do 12 chin-ups in 60 seconds.
Calculate the power developed by the student.
Gravitational field strength = 10 N/kg
Eg = mgh
= 65 x 10 x 0.4
= 260 J
total Eg = 260 x 12
= 3120 J
power = energy transferred/time
= 3120/60
= 52W
A student rubbed a plastic rod with a cloth.
The rod became negatively charged and the cloth became positively charged.
Explain why the cloth became positively charged.
Electrons were transferred from the cloth to the plastic rod.The cloth lost electrons, so it had more positive charges than negative.Losing electrons makes the cloth positively charged.
why would the mass increase if a charged rod is held over a negatively charged rod
The rods have like charges, so they repel each other.The top rod pushes the bottom rod downward without touching it.This increases the force on the balance, so the reading increases.
what is the difference between speed and velocity
Speed is how fast an object is moving; velocity is speed in a given direction.
The speed of the rocket just after being launched is 12 m/s.
The mass of the rocket is 0.05 kg.
Calculate the kinetic energy of the rocket just after being launched.
Ek = 1/2mv^2
= 1/2 x 0.05 x 12^2
= 3.6 J
As a rocket moves upwards, it gains gravitational potential energy. Ignoring air resistance, what is the maximum gravitational potential energy gained by the rocket if its kinetic energy just after launch is 3.6J
The maximum gravitational potential energy gained is 3.6 joules, equal to the initial kinetic energy (assuming no energy losses).
Calculate the maximum height a rocket will reach if it has a gravitational potential energy of 3.6 J, a mass of 0.05 kg, and gravitational field strength is 10 N/kg. Ignore air resistance.
Eg = mgh
h = Eg/mg
h = 3.6/(0.05×103.6)
=7.2m
What pattern links the angle at which the rocket.is launched and the range of the rocket?
The range increases up to 45 degrees and the range decreases from 45 degrees
the lamps in the circuits drawn below are all identical. Each of the cells has a potential difference of 1.5 volts. What is the potential difference across the 3 cells that are joined in series?
V total= 3 × 1.5 = 4.5 volts
which volt meter would give the highest reading
V2
when adding an ammeter…
add it on the left hand line of the circut
How can the potential difference of the battery be calculated from Figure 4, where voltmeter V₁ reads 9 V and voltmeter V₂ reads 3 V?
A) 9 + 3 = 12 V
B) 9 - 3 = 6 V
C) 9 + 3 = 3 V
A) 9 + 3 = 12 V, because the total potential difference of the battery equals the sum of the potential differences across all components in series.
when calculating distance on a velocity time graph you do…
change in time x change in velocity
if a parachutist jump out a plane how far will she fall before opening her parachute
570m
Just before the toy aeroplane is released, the spring has an extension of 0.12 m.
mass of aeroplane = 0.020 kg
spring constant of the spring = 50 N/m
Calculate the maximum speed of the toy aeroplane just after it is launched.
Give the unit.
Ee = 1/2ke^2
Ek = 1/2mv^2
mv^2 = ke^2
0.02 x v^2 = 50 x 0.12^2
0.02 x v^2 = 0.72
v^2 = 0.72/0.02
= 36
v = 6 m/s
calculate the acceleration of the parachutist at 4s.
draw tangent at 4
then:
60-4 = 56
56/7 = 8
density formula
Density = mass/volume
