Forces and Motion
When an apple falls down to the ground, which force is making it accelerate downwards?
Gravitational Force or Gravity
Why do some objects roll down faster than others even though they are round?
This is because rotational inertia is not constant. Rotational inertia varies depending on the shape of the object. You can solve for the different rotational inertia equations using derivations (from calculus)
When you drop a ball, why do you think the kinetic energy increases?
As you drop the ball, the acceleration causes an increase in velocity, which is directly proportional to kinetic energy (KE = ½ mv2)
When you pluck a guitar string, why does each string produce a different sound?
When a string is plucked its vibration is transmitted from the bridge, resonating throughout the top of the guitar
Does your house use a series or parallel circuit layout?
Most houses in the US use a parallel circuit layout since if one light bulb fails, it won't affect the entire house.
When you press down on a keyboard, what forces are acting on the object?
Applied, spring, gravitational, and normal force
If you were to roll a tire versus a solid cylinder down on an inclined ramp, which do you think would reach the ground first?
The solid cylinder would reach first because it has a greater rotational inertia
If a waiter is carrying a tray on the palm of their hand and is moving forwards, what is the work being done to the system?
Zero because the force applied is perpendicular to the displacement
If you were to speak in a vacuum, would you be heard?
No, because sound travels through particles
If you plug a wire into a large power source, why does the wire heat up?
This is because there is more current flowing through the wire, and more collisions of the electrons onto the wire will cause the wire to heat up.
You are in Great America, and you decide to go on the swing ride. Do you think your tangential velocity changes if you are traveling at a constant speed?
No, because velocity is a vector quantity. So, although the magnitude of the vector stays constant, the direction changes.
Why do your car tires not slide on ice but roll on the road?
It's due to friction.
If you and a car collide and after you collide, you stick together and move in the same direction, are kinetic energy and momentum conserved?
Kinetic energy is not conserved because this is an inelastic collision and momentum is always conserved
How many of the following can we see through the naked eye: gamma rays, x-rays, visible light, and ultraviolet rays?
One; only visible light
Do lightning strike the same place twice?
Lightning can strike the same place twice. Lightning usually goes for the highest point since it is the easiest path for electrons to flow.
Which scenario would the ball reach the ground faster?
Scenario A: You throw the baseball forward as hard as possible.
Scenario B: You drop the baseball without any force
Both reach the ground at the same time
A box and a tyre roll down a ramp, which one has a greater speed?
The box will have a greater speed since gpe is converted to both translational and rotational kinetic energy for the rolling object
When a ball at a billiard table hits another ball, is kinetic energy and/or momentum conserved? Why or why not?
Kinetic energy is conserved because this is an elastic collision and momentum is always conserved
If you are driving and have to look at your side-view mirrors, what type of mirror do you think they are? Convex, concave, or parabolic?
Convex mirrors in order to give the driver a wider field of view and minimize blind spots
What causes a magnet to be a magnet?
In simple terms, the electrons in the magnet spin the same way, causing a magnetic field.
When you and a truck 3 times your side collide, is the truck's force on you greater than your force of the truck?
Due to Newton’s Third Law pairs, you and the truck will have an equal amount of force on each other.
If an object rolls down a ramp, which one is greater, the translational or rotational kinetic energy?
They are both the same
When a car is driving on the road, does it have to increase its velocity to maintain a constant level of energy?
No, because the greater change in velocity causes a greater change in acceleration, which affects the work done by friction. Friction always causes a loss in energy
When you hear an ambulance zoom by, why do you hear a difference in the change in pitch as it passes you?
It’s because of the Doppler effect. As it approaches, the siren's pitch sounds higher than when it is moving away from you.
Why does your hair flow up when balloon is rub against your hair?
When a balloon is rubbed against your hair, your hair loses electrons to the balloon. That’s why your hair moves away from each other since like charges repel each other.