Computing an equation

Question

Steven 2012-2-18

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编辑： Azzi Abdelmalek 2013-10-16

I am suppose to find the height and distance traveled by a ball thrown at angle A and a speed v given by:

h(t)=v*t*sin(A)-(1/2)*g*t^2
x(t)=v*t*cos(A)

I am given:

gravity=g=9.81m/s^2
v=10m/s

and the angle A = 35

I know I just plug those into the equations to solve for h(t) and x(t) but I am not given the time "t" so how am I suppose to get t?

I am suppose to compute how high the ball goes, how far it will go, and how long it will take to hit the ground.

PLEASE HELP ME!!!

Part b of the problem asks for "Use the values of v and A given in part a to plot the ball's trajectory; that is, plot h versus x for positive values of h"

How can I do this is we just solved for the exact value of h and x?, we need multiple values of h and x to plot.

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bym 2012-2-18

What do you know about the ball's velocity at the maximum height? What do you know about the ball's height at the time when it hits the ground?

Steven 2012-2-18

all it gives me is that the velocity is 10 m/s and the gravity and angle that I stated above. I am not given time so how can I figure it out? I know the the answers to the question because they are stated in the back of the book but I don't know how to work my way to the answer. The answers are: ball rises 1.68m high, it will travel 9.58m, and it hits the ground in 1.17s. Those are the answers, hopefully this gives you something to work on.

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Answer 1

Krishnendu Mukherjee 2012-2-18

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make that two functions in function builder.give the time input as a ramp function,f(t)=t;[may t=0:10] add a scope.find the answer

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Steven 2012-2-18

The answers to this selected question was posted in the back of my textbook lol

Krishnendu Mukherjee 2012-2-19

why multiple answer?if u would give a ramp as input.then for different values the different answer would shown as continous signal.you could see.for which value of t maxima is arrising.

why unnecessarily u will make a complicated program?thats why i hv tld that

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Answer 2

Andrei Bobrov 2012-2-18

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在 MATLAB Online 中打开

syms t
A = 35;
g = 9.81;
v = 10;
h = v*t*sind(A)-(1/2)*g*t^2;
x = v*t*cosd(A);
t_hmax = solve(diff(h,t),t);
hmax = vpa(subs(h,t,t_hmax),5)
x_all = vpa(2*subs(x,t,t_hmax),5)

ADD

xf = matlabFunction(x);
hf = matlabFunction(h);
t2 = linspace(0,2*double(t_hmax),100);
plot(xf(t2),hf(t2))

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Steven 2012-2-18

Part b of the problem asks for "Use the values of v and A given in part a to plot the ball's trajectory; that is, plot h versus x for positive values of h"

How can I do this is we just solved for the exact value of h and x?, we need multiple values of h and x to plot.