A flat, solid cylindrical grinding wheel with a diameter of 24.2 cm is spinning at 3000 rpm when its power is suddenly turned off. A workman continues to press his tool bit toward the wheel's center at the wheel's circumference so as to continue to grind as the wheel coasts to a stop.
If the wheel has a moment of inertia of 4.99 kg⋅m2 , the necessary torque (116 m*N ) must be exerted by the workman to bring it to rest in 13.5 s .
If the coefficient of kinetic friction between the tool bit and the wheel surface is 0.800, how hard must the workman push on the bit?(in newtons)
In: Physics
1.You are the science officer on a visit to a distant solar system. Prior to landing on a planet you measure its diameter to be 18,000 km and its rotation period to be 22.3 hours. You have previously determined that the planet orbits 2.2 X 108 km from its star with a period of 402 earth days. Once on the surface you find that the free-fall acceleration is 12.2 m/s2.
What is the mass of the planet?
What is the mass of the star?
2.In 2000, NASA placed a satellite in orbit around an asteroid. Consider a spherical asteroid with a mass of 2.7 X 1016 kg and a radius of 5.8 km.
What is the speed of a satellite orbiting 3.4 km above the surface?
What is the escape speed from the asteroid?
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The cue ball collides with the 8-ball on a pool table. Before the collision, the 8-ball was stationary, and the cue ball was moving east with a speed of 9 m/s . After the collision, the 8-ball moves at an angle of 45 ∘ south of east with a speed of 4 m/s . Right after the collision, what is the component of the cue ball's velocity that points east? You may assume the two balls have the same mass. Right after the collision, what is the component of the cue ball's velocity that points north?
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A pilot ejects from his stalled plane with an upward velocity of 17m/s and no horizontal velocity. Calculate his velocity at each time given. (Ignore air resistance for this part) t = 1.0s: ______________ t = 1.7344s: ________________ t = 2.0s: ______________ t = 3.46689s: _______________ t = 227s: ________________
In: Physics
In: Physics
A contact lens is made of plastic with an index of refraction of
1.30. The lens has an outer radius of curvature of +1.96 cm and an
inner radius of curvature of +2.56 cm. What is the focal length of
the lens?
___cm
In: Physics
A block of mass m = 2.00 kg is released from rest at h = 0.600 m above the surface of a table, at the top of a ? = 40.0
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A projectile is launched at an angle of 30 degrees above the horizontal at a speed of 300 m/s. In what direction is it traveling after 3 s? In other words, what is the direction of its velocity vector? (Use |g| = 10 m/s2.)
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A 39 g block of ice is cooled to −67◦C. It is added to 518 g of water in an 64 g copper calorimeter at a temperature of 28◦C.
Find the final temperature. The specific heat of copper is 387 J/kg ·◦C and of ice is 2090 J/kg ·◦C . The latent heat of fusion of water is 3.33 × 105 J/kg and its specific heat is4186J/kg·◦C.
Answer in units of ◦C.
In: Physics
In: Physics
A 11.7kg weather rocket generates a thrust of 200N . The rocket, pointing upward, is clamped to the top of a vertical spring. The bottom of the spring, whose spring constant is 550N/m , is anchored to the ground.
A) Initially, before the engine is ignited, the rocket sits at rest on top of the spring. How much is the spring compressed?
B)After the engine is ignited, what is the rocket's speed when the spring has stretched 32.0cm ?
C)For comparison, what would be the rocket's speed after traveling this distance if it weren't attached to the spring?
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A stick is resting on a concrete step with 1/7 of its length hanging over the edge. A single ladybug lands on the end of the stick hanging over the edge, and the stick begins to tip. A moment later, a second, identical ladybug lands on the other end of the stick, which results in the stick coming momentarily to rest 46.5° from the horizontal. If the mass of each bug is 3.43 times the mass of the stick and the stick is 16.3 cm long, what is the magnitude of the angular acceleration of the stick at the instant shown?
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In a game of basketball, a forward makes a bounce pass to the center. The ball is thrown with an initial speed of 4.9 m/s at an angle of 20 ∘ above the horizontal. It is released 0.80 m above the floor.
What horizontal distance does the ball cover before bouncing?
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Describe the differences between circular motions and elliptical motions. Explain how Newton’s universal gravitational law can be applied to study the interplanetary motions.
In: Physics
In: Physics