Projectiles
A ball dropped off of a cliff, a bullet fired from a gun, and the Moon are all one of these.
What is a projectile?
First Hand ($100): What is the definition of a projectile?
This is the difference between rotational and tangential velocity.
Rotational velocity is how much of a circle is completed per second, but tangential velocity is how much distance a point on the circle is traveling per second.
or
Rotational velocity only depends on the time of a lap, tangential velocity depends on time and radius.
This is the result of the Moon's gravity pulling on the Earth's oceans as the Moon revolves around the Earth.
What are the tides?
This is the torque created by a 5N force that is located 3 meters from the fulcrum.
What is 15 N*m?
This is the value for G, the universal gravitational constant.
What is 6.67 * 10-11?
First Hand ($100): What are the units for this constant?
This is the acceleration for the horizontal component of motion for a projectile.
What is 0 m/s2?
What is inertia?
Describe how the center of gravity moves when an object in stable equilibrium is displaced (pushed on/tipped).
The center of gravity moves up as the object is tipped.
First Hand ($100): Describe the motion of the COG for an object in neutral equilibrium when it is displaced.
These are the two ways to increase torque.
What is increasing the force and increasing the lever arm length?
First Hand ($100): What should be true about the angle at which the force is applied to maximize the torque?
This is the gravitational force at the center of the Earth.
What is 0 m/s2?
First Hand ($100): Why?
This is the time it would take for an object launched straight up at a velocity of 30 m/s to reach its peak height.
What is 3 seconds?
This force provides the centripetal acceleration for a car turning a corner on a flat road.
What is friction?
First Hand ($100): If the car starts slipping, what are 2 things the driver can do to get back into a circular path?
If the Sun's gravity was suddenly turned off, this is what would happen to the Earth.
The Earth would continue flying tangentially forward through space in a straight path.
This is the weight needed at a distance of 4 meters from the fulcrum to balance a 70N weight placed 3 meters from the fulcrum.
What is 52.5N?
Who experiences more gravitational attraction, the Earth or the Moon?
Both.
First Hand ($100): Who experiences more gravitational acceleration?
A baseball is thrown straight sideways off the top of the gym at a speed of 25 m/s. If the gym is 45 meters tall, how long will it take for the ball to hit the ground?
What is 3 seconds?
First Hand ($100): How far from the gym will it land?
A mouse on the edge of a spinning record with a radius of 10 cm completes 2 revolutions every second. What is the mouse's rotational velocity, tangential velocity, and centripetal acceleration?
w = 12.6 rad/s
v = 1.26 m/s
ac = 15.8 m/s2
This made sure that the weight of the meterstick didn't cause an additional torque by keeping its weight at a lever arm of 0.
Explain (in terms of forces, lever arms, and torques) why one must balance a hammer at a point that is not in the middle of the hammer's length.
Explain why objects on Earth experience a force of gravity even though they are touching the surface of Earth.
Gravity is due to the distance between both objects' centers of mass. The Earth's center of mass is one radius away (6.4 x 106 m) from its surface, so this is the distance between the Earth's mass and the objects on the surface.
Dionne hits a golf ball from the tee box on a par 4 with a velocity of 50 m/s at an angle of 60o from the ground. If the hole is 250 meters away, will the ball land in front of or behind the pin?
Assume the tee box is level with the pin on the green.
The ball will land in front of the pin.
First Hand ($100): Assuming the ball didn't roll at all from where it landed, how far will Dionne have to putt to get a birdie?
How fast can you spin a 10kg ball on a string with a maximum tension of 20N to keep it in a circle with a radius of 2 meters without the string snapping?
v = 2 m/s
First Hand ($100): What will the rotational velocity be?
What is wrong with the clock in the physics classroom?
A 10-m plank with a mass of 15kg is laid on the edge of a cliff with 4 meters of the plank sticking over the side. If a 50kg person stands on the end of the supported side of the plank, how much mass can be stacked on the end of the unsupported side of the plank before it tips over? Hint: draw a picture with all of the lever arms and forces.
What is 78.75kg?
This is the mass of the Earth. NO GOOGLING.
Earth's radius = 6.4 * 106 m
G = 6.67 * 10-11 N*m2/kg2
What is 6 * 1024 kg?