Tagged Questions
0
votes
1answer
45 views
Projectile's angle in midflight
For a missile travelling from (0,0) at angle $\theta$ (to the horizontal) and initial velocity $u$, the y (vertical) position at time t is given by
$s_{y} = u\sin (\theta) t - 0.5gt^{2}$
and the x ...
1
vote
2answers
90 views
Doubt in Kinematics
I know that this isn't the place for such basic questions, but I didn't find the answer to this anywhere else. It's pretty simple: some particle moves in straight line under constant acceleration from ...
0
votes
2answers
141 views
Equation of motion for average acceleration
I am trying to solve the following:
A man of mass 83 kg jumps down to a concrete patio from a window ledge only 0.48 m above the ground. He neglects to bend his knees on landing, so that his ...
0
votes
0answers
54 views
At an acceleration of 2ft/s^2, how fast could I reach 9.8MPH? [closed]
Question title is self explanatory.
If I'm accelerating at $2ft/s ^{2}$, how long does it take to reach $9.8MPH$?
0
votes
0answers
54 views
Accelerated motions of a car and a truck [closed]
A car and a truck start from rest at the same instant with the car initially at same distance behind the truck. The truck has constant acceleration of 3.4 m/s^2. The car overtakes the truck within the ...
0
votes
2answers
165 views
Calculating vertical velocity component of a particle with mass, given the hit point of parabolic motion
Consider the following situation:
I have a particle with a given mass that at a given instant of time (let's say $t_{0}$) is placed at the system origin. The particle has a constant velocity ...
3
votes
1answer
300 views
How do I find the initial velocity in this problem?
An X-ray tube gives electrons constant acceleration over a distance of $20\text{ cm}$. If their final speed is $2.0\times 10^7\text{ m/s}$, what are the electrons' acceleration?
I know this ...
-2
votes
1answer
404 views
Calculate acceleration and time given initial speed, final speed, and travelling distance? [closed]
A motorcycle is known to accelerate from rest to 190km/h in 402m.
Considering the rate of acceleration is constant, how should I go about calculating the acceleration rate and the time it took the ...
0
votes
2answers
88 views
Proof of $T=\sqrt{2y/a}$ in uniformaly accelerating object [closed]
Suppose that there is a object that does a y-axis-only free fall to ground. The initial distance from the ground is defined as $H$.
How does one prove that time the object takes to reach the ground ...
0
votes
1answer
126 views
Proving $t=(1+\sqrt{1+2hg/v^2 } ) (v/g)$ for a thrown ball
If we throw a ball from the hight point $h$ from the earth, with initial velocity $v’$, how to prove that the time it takes the ball to reach the earth is given by:
...
0
votes
0answers
74 views
Jumping on a landing pad [closed]
I'm trying to make a character jump on a landing pad who stays above him. Here is the formula I've used (everything is pretty much self-explainable, maybe except character_MaxForce that is the total ...
0
votes
0answers
200 views
Projectile Motion
I know the angle at which a projectile is launched, how far it needs to go, and also the maximum height. How can I find the initial velocity needed (disregarding air resistance)?
Currently, I am ...
0
votes
2answers
822 views
How do you calculate angle of projection?
At what angle the projectile should throw with initial velocity v in order to reach distance d? discard the air resistance, only gravitation acts. So far I got the equations for horizontal and ...
0
votes
0answers
109 views
Confusing elevator Question , Please help by giving answer and detailed procedure [closed]
The given data is :
An elevator starts from rest and is uniformly accelerating at 2m/s2 . After 1 second , a person throws up a ball with initial velocity 4m/s. The hands of the thrower remain in ...
0
votes
1answer
2k views
Finding deceleration and velocity using distance and time
A car is moving down a street with no brakes or gas. The car is slowing due to wind resistance and the effect of friction. The road is flat and straight. The only data I have are timings taken at 100m ...
3
votes
3answers
361 views
A freefalling body problem, only partial distance and time known
Well, I've been trying to figure out a problem which I imposed on myself, so no literal values included. Unfortunately, my brain is not cooperating.
The problem states:
What is the height from ...
-1
votes
1answer
369 views
The acceleration of a particle moving only on a horizontal plane is given by a= 3ti +4tj, [closed]
The acceleration of a particle moving only on a horizontal plane is given by a= 3ti +4tj, where a is in meters per second-squared and t is in seconds.
At t = 0s, the position vector r= (20.0 m)i + ...
1
vote
2answers
74 views
Acceleration: Value Disparity?
If we consider a ball moving at an acceleration of $5ms^{-2}$, over a time of 4 seconds, the distance covered by the ball in the first second is $5m$. In the 2nd second will $5 + 5 = 10m$. In the ...
0
votes
2answers
775 views
What do I need to do to find the stopping time of a decelerating car? [closed]
The question is:
A car can be stopped from initial velocity 84 km/h to rest in 55 meters. Assuming constant acceleration, find the stopping time.
Sorry for my ignorance, but I need to review ...
0
votes
2answers
177 views
Why wouldn't this system of equations determine where two balls meet?
A ball is thrown vertically upwards at $5\text{ m/s}$ from a roof top of $100\text{ m}$. The ball B is thrown down from the same point $2\text{ s}$ later at $20\text{ m/s}$. Where and when will ...
0
votes
1answer
122 views
I think I disprove this with kinematics, but energy says it is right
!
Here is my kinematics argument. For now I am only going to look at ball 2 and ball 3. Make note of the following data.
$|v_0| = 10m/s$, $y_0 = 10m$, $\theta_2^0 = 30^0$, $\theta_3^0 = -45^0, g = ...
