1
vote
0answers
21 views

Finding equation for acceleration using mass1, mass2, gravity, theta, and Mu [on hold]

So, the only question I could not solve in this chapter for AP Physics, and I really want to understand it. We have a situation like this: There is a box sitting on an incline. We are trying to ...
0
votes
1answer
37 views

Why does the expression for this object's velocity have -T in it? [closed]

The original question: At $t = 0$, an object of mass $m$ is at rest and at $x = 0$ on a horizontal, frictionless surface. A force in the $x$ direction: $$ F(t) = F(0) e ^{-t/T} $$ is ...
1
vote
1answer
40 views

Finding the acceleration given only an angle

This is one of my homework problems for a College Physics I course: Dana has a sports medal suspended by a long ribbon from her rearview mirror. As she accelerates onto the highway, she notices ...
1
vote
2answers
43 views

Derivation of the average Velocity formula with constant acceleration (using calculus)

I have been looking at $$ v_{avg} = \frac{v_{i} + v_{f}}{2}, $$ when the acceleration is constant, where $v_i$ is equal to the initial velocity and $v_f$ is equal to the final velocity. How can ...
1
vote
1answer
78 views

A question about finding average velocity and average acceleration

I have trouble understanding the following problem's answer: Which of the following relations are true for any arbitrary motion in space? (a) $v_{avg}=\frac{r(t_2)-r(t_1)}{t_2-t_1}$ ...
-1
votes
1answer
49 views

Direction of radial acceleration same in circular motion?

I have a big confusion. There is a question in my book which basically says that a ball is tied to a string and rotated. and it asks me to tell whether the following statement is true of false. ...
0
votes
2answers
60 views

A problem says : a car starts from rest and undergoes a constant acceleration. It travels 5 m in the…? [closed]

A problem says : A car starts from rest and undergoes a constant acceleration. It travels 5 m in the t interval 0 s to 1 s, find the displacement of the car during the time interval from 1 s to 2 ...
0
votes
1answer
37 views

Average acceleration when more than two different velocities occur [closed]

Suppose a car travels at 5m/s north for 5 seconds, it then turn east and travel at 7m/s for 10 seconds, finally it turns north east and travel at 10 m/s for 20 seconds. What is the average ...
5
votes
2answers
354 views

The acceleration vector of a simple pendulum

In this picture the acceleration vector $\vec{a}$ points upward when the pendulum is halfway Click To see animated GIF But according to this picture, the force acts tangentially: Which means the ...
1
vote
2answers
134 views

How can Excel be used to model the flight of a rocket? [closed]

Firstly, sorry for any silly mistakes or improper use of this website - this is my first time using it! I am trying to use Excel to model the flight of the Apollo 11 Saturn V rocket using the real ...
1
vote
2answers
121 views

What is the relative acceleration of a projectile fired at in a low gravity vacuum?

This question is to end an old argument. Given a (space) vehicle with an acceleration of X, and projectile with an acceleration of 2X (rocket, not bullet), what would the relative acceleration of the ...
0
votes
0answers
28 views

How to calculate the equation of projectile motion for curved ramps? [duplicate]

Consider the following cases (these are sections): I can find the equation of motion for Case a however I don't know how to deal with Case d. Normally I would need the angle α otherwise I can't ...
2
votes
1answer
129 views

How to find equation of motion for this trajectory? - object leaves curved ramp at a given velocity [closed]

Here is the sketch: The sketch is supposed to be side-view of the path of the object. The following values are known: $r$ - radius of the circle that describes the path AB of the object $a$ - ...
0
votes
1answer
60 views

Have I calculated Angular Acceleration correctly?

I am teaching myself basic mechanics from a standing start. I am trying to understand Angular Acceleration and have set myself a problem to solve. My answer 'feels' wrong, so I'd like some help to ...
0
votes
2answers
44 views

Finding out the velocity [closed]

Displacement of an object is related to time $x=at+bt^2-ct^3$ where a, b and c are constant motion.Then the velocity of an object when it's acceleration is zero is given by ...
1
vote
1answer
62 views

Travel time for accelerating object [closed]

I have an object which starts at velocity = 0. Accelerates to a known max speed and continues thereon at constant velocity (max speed). My problem: How long does it take to reach a known ...
2
votes
1answer
27 views

am i finding the force correctly?

I am trying to see if I am doing a problem correctly. Problem Suppose you carry a 50kg sack of potatoes up two flights of stairs, a total height of 10m. How much work did you do? If it took you ...
2
votes
1answer
81 views

How to get time from equation of linear uniformly accelerated motion?

I have had a problem solving this equation for time (from Linear Uniformly Accelerated Motion (LUAM)): $$ s= v_0t + \tfrac{1}{2}at^2 $$ I'll appreciate if someone could provide me some step-by-step ...
2
votes
3answers
76 views

How to calculate the velocity of this body? [closed]

Graph of a train (the body) is provided which starts from rest. What is the velocity after the train has 10 metres displacement? Thats the only things provided for the question, please help me ...
0
votes
1answer
204 views

Truck moving uphill, object suspended from ceiling, determine acceleration [closed]

A truck is moving with constant acceleration $a$ up a hill that makes and angle $\phi$ with the horizontal. An object of mass $m$ is suspended from the ceiling of the truck by a light cord. If the ...
2
votes
2answers
226 views

What is wrong with considering the Atwood machine as a system?

I am confused about a method used in the following problem. There is an arrangement as shown below. The surface is smooth, and the pulleys are light. We have to find the acceleration $a_0$ of $m_1$. ...
0
votes
1answer
48 views

Acceleration ratio

Can anyone please explain why: $$a_1=a_2\tan\alpha $$ We have 2 same cubes placed on a platform, between them there is a wedge which is pushing the cubes in opposite directions. The hard part of the ...
-1
votes
1answer
34 views

How to calculate Acceleration

Assume you are moving 10 meters in 10 seconds northward. What is the acceleration?. Using this equation: $a = (v_f - v_o)/\Delta(t)$ and filling it in with this data: $v_f=1$ which comes from $10$ ...
-1
votes
2answers
48 views

Free fall question: Bill shoots his gun [closed]

Bill borrows his dad's gun and when he gets outside he fires it straight up into the air. If the bullet left the gun at 400 m/s: How long does it take the bullet to reach its highest point. I know ...
-1
votes
1answer
39 views

Acceleration Power [closed]

Suppose we have a trolley currently at rest at point A, but the motor switches on, so that it accelerates and reaches point B, at point B, the velocity is 5m/s, Distance of A-B is 10m, mass of the ...
0
votes
1answer
56 views

Kinematics with non constant acceleration II [closed]

I'm getting crazy with this problem and I think that it's pretty simple. An helicopter's helix is spinning at initial speed $w_0=200\ rpm$, all of a sudden the motor stops and it decreases its ...
2
votes
2answers
55 views

Acceleration of chairlift [closed]

So I'm struggling with this question, and am wondering if anyone can give me the right direction to go. For the sake of not cheating, I've changed the figures etc. I just need help on the approach. I ...
0
votes
1answer
54 views

What is a realistic launch speed of a grappling hook gun? [closed]

In The Dark Knight, at the end of the movie Batman throws the Joker off of a building and then shoots his grapple hook gun to catch him. Is 68m/s a reasonable speed for a grapple gun to shoot?
1
vote
3answers
94 views

Cart on Ramp with Varying Acceleration

For a lab that I have to do, the teacher has given me a data table of the displacement of a cart on a ramp after successive intervals of time. I have used this data to derive the velocities and ...
0
votes
2answers
29 views

What is the acceleration of a two weights connected with wire?

Given 2 weights: m1 = 2 kg m2 = 1 kg They are connected with wire hung over stick and considering there are no wire friction. Find the acceleration of weight m1 going down. Find the (force) tension ...
-1
votes
1answer
24 views

How much time would take to lift a person to 0.1m above floor of elevator? [closed]

How much time would take to lift a person to height $h$ above floor of elevator if the elevator goes down with acceleration $a$, where: $$h=0.1 \; \text{m}$$ $$ a=13 \; \text{m}/\text{s}^2 $$ How to ...
0
votes
2answers
61 views

Acceleration during collision with ground

For my physics class, I have to calculate an objects acceleration while it came to a stop. It was traveling at $6.26\: \mathrm{\frac{m}{s}}$ at impact, and travels a distance of $0.025\: \mathrm{m}$ ...
0
votes
0answers
298 views

Inclined plane problem

FOR THE GIVEN PROBLEM AND SOLUTION BELOW 1) The problem statement, all variables and given/known data: A student pulls on a box up an incline of 10 degrees. The student pulls with a force of 180 ...
0
votes
2answers
172 views

2 bodies separated by a rope [closed]

Say you have two bodies connected by a "weightless" rope, one hanging from a ledge on a pulley (classic pulley problem). If the body that is on the surface and being pulled by the object hanging ...
-1
votes
1answer
75 views

What is the frictional force of this car? [closed]

The breaking acceleration for a car is $-12.2\frac{m}{s^2}$. The car has a mass of 925kg. I want to find the frictional force. Here is what I have so far: $$\Sigma\vec{F} = m\vec{a}$$ $$\Sigma\vec{F} ...
1
vote
2answers
61 views

Position with respect to time with friction

I'm interested in equations of motion when friction is present for a little graphical side project I am working on. I'm really rusty with physics, so I apologize if this is a basic question or doesn't ...
0
votes
1answer
140 views

What is this vector problem asking to find, the magnitude of the force F or the component of it that goes along the ramp?

A shopper pushes a 7.5-kg shopping cart up a 13 (degree)incline. Find the magnitude of the horizontal force, F, needed to give the cart an acceleration of 1.41 m/s$^2$. I ask this because the ...
0
votes
2answers
113 views

How to find time, acceleration under this situation

I am trying to solve the following. An object of mass $m$ slides on a horizontal surface with initial velocity $v_0$. If the kinetic friction between the object and mass is given by $\mu$, find ...
0
votes
3answers
138 views

Net force and its concept

I am trying to understand net force intuitively and this is what I think. If a net force is towards the positive $x$ direction, which of the following is true ? a) It can be moving in the ...
2
votes
1answer
115 views

How long would it take a projectile accelerating twice as fast as another to catch up?

Given a projectile with initial velocity $u$, and constant acceleration $a$, travelling in the one direction. How long would it take a second projectile the same as the first with the same initial ...
-3
votes
1answer
44 views

Acceleration on an inclined rail [closed]

I have to use $\vec{P}+\vec{R_N}+\vec{F_f}=m\vec{a}$ with $\|\vec{F_f}\|=\mu\|\vec{R_N}\|$ to express the acceleration as $$a_{x'}=g\sin\alpha(1-\frac{\mu}{\tan\alpha})$$ The configuration is (sorry ...
0
votes
0answers
70 views

Transformation of a time-dependent acceleration to another frame

How do I transform a time-dependent acceleration between to rest frames? I was given a particular problem and while I found possibilities [1] [2] for acceleration-transformations when the acceleration ...
-2
votes
2answers
388 views

Explain what happens to object in lift [closed]

In the following image,three cases have been mentioned. $N$ is the normal force acting on the object inside the lift and $mg$ is the force of attraction due to gravity. In case 1, $N = mg$. In case ...
8
votes
2answers
266 views

What is the physical meaning of $|f''(\xi )|\leq\frac{4(f(b)-f(a))}{(b-a)^{2}}$ where $f(t)$ is position as a function of time?

Here is the full problem: I was able to prove the given expression; but the interpretation part is giving me a bit of trouble. Here is my interpretation: The average acceleration in $(a,b)$, is ...
1
vote
0answers
22 views

How far will the first spacecraft travel before the second one catches up to it? [closed]

A spacecraft leaves the point of origin and has a maximum acceleration of 30 m/s. It can only maintain this rate for 10 minutes before it runs out of gas and then proceeds to drift at a constant ...
1
vote
2answers
153 views

How to work out the acceleration of an object

I got given this question and im just lost. An object that weighs 25 kg experiences two perpendicular forces of 80N and 50N respectively. What's the acceleration that object gets? What i ...
0
votes
2answers
54 views

How to get $t$ from $a(v)$?

I read what if we have acceleration given as a function of velocity we can calculate time as $$t(v) = t_0 + \int_{v_0}^{v} \frac{dv}{a(v)}.$$ Why?
0
votes
0answers
230 views

A force F pushes an inclined plane M with a block on the incline; find acceleration up the incline

So there is an inclined plane of mass $M$ that is pushed with a force $F$. A block of mass $m$ is on the inclined plane that accelerates up along the inclined plane due to the pushing of $M$ by force ...
0
votes
0answers
106 views

g as a function of Theta

I slide an object down a ramp of a certain length, which is inclined at a certain angle $\theta$. It reaches the bottom in time $t$. Assuming that no forces act on the object other than gravity and ...
0
votes
3answers
5k views

Calculate average acceleration without time? [closed]

I have a question about a flea jumping, for which I need to show that the average acceleration is around 1000 $ms^{-2}$. I know that to calculate average acceleration you can use $\frac{dv}{dt}$, ...