Kinematics
Starting from rest, an object accelerates on a straight level surface at a rate of 2 m/s2 for 10 seconds. What is the speed of the object at the end of 10 seconds?
20 m/s
Gravitational Potential Energy and Spring Potential Energy
What is an Elastic Collision?
A ball is dropped from a height h. A second ball is thrown vertically upward from the ground with an initial velocity v0. Derive an expression for the time t that the balls pass each other.
t = h/v₀
The type of energy that dictates work done in a system when there are no non-conservative forces
What is potential energy
These two properties must hold for a system to be considered a Closed System
1. Sum of External Forces must equal the rate of change of total momentum over t
2. The rate of change of mass must equal 0 (ie no change in mass can occur over t)
A car moves in uniform circular motion around a banked curve below the maximum tangential speed. The components of these forces contribute to the centripetal force
What is Normal Force and Static Friction?
An object starts from rest at t=0s. The velocity v(t) is given by v=2t+3t2. How far does the object travel in the first 5 seconds?
150 meters
This force provides the external force that accelerates a car driving on a flat road
What is Static Friction?
https://snipboard.io/Ju2byX.jpg
You are on a cart, initially at rest, on a track with very little friction. You throw a ball to the left at a partition that is rigidly mounted on the cart. If the ball bounces straight back to the right, will the cart ever move? In what direction? Why? (all questions must be answered correctly for credit)
1. Yes
2. The cart moves to the left
3. Momentum is conserved before and after the collision. Since the ball is moving to the right, in order for momentum to be conserved, the cart must move to the left
The magnitude of Kinetic Rotational Energy of a sphere of mass m and radius R pushed on a frictionless surface by force F_A to translational velocity v_f
What is 0?
An object moving in a straight line has a velocity v in m/s that varies with time t in seconds, according to the following function: v=8t+2.5t3 What is the instantaneous acceleration at t=2s?
38 m/s²
https://snipboard.io/p8iEaT.jpg
Assume that the motorcycle reaches the loop with initial velocity v0 that is great enough to complete the loop. This is the point of the loop where the Normal Force acting on the motorcycle is the greatest
What is 1?
A block from initial height h slides down a frictionless curved incline. Is the block's energy entirely conserved?
No. The normal force is non-conservative and acts on the block.
Explain why cars with airbags have a lower mortality rate than cars without airbags during a car crash using physics terms
In a car collision, initial momentum of the driver is the same regardless of the airbag, and the final momentum is 0 when the person is at rest.
Airbags increase the amount of time it takes for the person to come to rest. Since the time it takes for the person to come to rest increases in the airbag case, the average force acting on the person over time is lower.
The acceleration of a moving object is a=9t2. The object has an initial position of -2 m and is travelling with a velocity of 3 m/s in the negative x direction. At what time is the acceleration of the object 38 m/s/s?
38m/s^2 over 2.05 ( or √38) seconds
https://snipboard.io/VYNFuh.jpg
Assume that L is the length from the top of the incline to the bottom, and that the spring shown begins at an unstretched length of L/3. Given that the block and spring shown are on a frictionless surface, derive an equation for what mass m should be such that the spring extends to the bottom of the incline
(2/3 * k * L) / (gsinθ)
https://snipboard.io/Z6GdTx.jpg
A skier of mass m is initially at rest on a steep and very icy hill (essentially no friction) that makes an angle θ with level ground. They start down the ski run
and travel a distance L along the slope before reaching level ground. There’s a ton of powder at the bottom, and the thick powdery snow exerts a kinetic friction force F_k on the skier. The skier
continues to slide for some distance, and then comes to a stop. What is the value of the work done on the skier by friction at the end of the ski run? Express your
answer symbolically in terms of known quantities.
-mgLsin(θ)
Consider a sled of mass m sliding over a horizontal surface in a straight line. At t_i, the speed of the sled is v. At some time later, the speed of the sled is v/2. Derive an expression for the coefficient of kinetic friction between the sled and the surface. Explain your methodology.
µ_k = v /2g(∆t).
See PHYSICS 41 Topic 19 Breakout 1-c for an explaination.
The Aquario 105F is a Beyblade Tip that switches modes as the bey spins. (if you don't know what a beyblade is, its a spinning top)
When the bey is spun, it begins with angular speed ω0 about its center of mass, with mass m and a radius of r. When the mode change occurs, the bey's radius changes to a radius of r/2. Both can be modeled as a uniform disk. What is ω1 in terms of ω0?
ω₁ = 4ω₀