Answer:
1.41 m/s^2
Explanation:
First of all, let's convert the two speeds from km/h to m/s:
Now we find the centripetal acceleration which is given by
where
v = 12.8 m/s is the speed
r = 140 m is the radius of the curve
Substituting values, we find
we also have a tangential acceleration, which is given by
where
t = 17.0 s
Substituting values,
The two components of the acceleration are perpendicular to each other, so we can find the resultant acceleration by using Pythagorean theorem:
Answer:
a) 0.138J
b) 3.58m/S
c) (1.52J)(I)
Explanation:
a) to find the increase in the translational kinetic energy you can use the relation
where Wp is the work done by the person and Wg is the work done by the gravitational force
By replacing Wp=Fh1 and Wg=mgh2, being h1 the distance of the motion of the hand and h2 the distance of the yo-yo, m is the mass of the yo-yo, then you obtain:
the change in the translational kinetic energy is 0.138J
b) the new speed of the yo-yo is obtained by using the previous result and the formula for the kinetic energy of an object:
where vf is the final speed, vo is the initial speed. By doing vf the subject of the formula and replacing you get:
the new speed is 3.58m/s
c) in this case what you can compute is the quotient between the initial rotational energy and the final rotational energy
hence, the change in Er is about 1.52J times the initial rotational energy