13. A uniform solid ball first rolls purely along a floor,
then up a ramp inclined at 30°. It momentarily
stops when it has rolled 1.5 m along the ramp. Its
initial speed is approximately
Answers
Answer:
Explanation:
Given A uniform solid ball first rolls purely along a floor,
then up a ramp inclined at 30°. It momentarily
stops when it has rolled 1.5 m along the ramp. Its
initial speed is approximately
We know that according to law of conservation of energy we get
E pot = E translation + E rotation
We know that E translation = mv^2 / 2 (initial translational kinetic energy of ball, E rotation = lω^2 / 2 is initial rotational kinetic energy of the ball.
Now E pot = mgh = mgl sin 30 is final gravitational potential energy of ball.
For solid ball l = 2/5 mr^2 where m is mass and r is radius.
So E rotation = lω ^2 / 2 = l / 2 2/5 mr^2 ω^2
= mv^2 / 5
So mv^2 /2 + mv^2 / 5 = mgl sin 30
7/10 v^2 = g l ½
Now initial speed
V = √5 g l / 7
= √5 x 9.8 x 1.5 / 7
= 3.24 m / s
Explanation:
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