A tennis player serves a hall horizontally at 30.0 m/s. If he hits the ball at a

Question

A tennis player serves a hall horizontally at 30.0 m/s. If he hits the ball at an elevation of 2.7 in, what will be the magnitude of its velocity when it strikes the ground? (Ignore air resistance.) 37.3 m/s 22.7 m/s 52.9 m/s 34.2 m/s 30.9 m/s Two blocks of mass 1.0 kg and 3.0 kg start from rest and move down an inclined plane. The coefficients of kinetic friction for both blocks are the same. The acceleration for the 3.0-kg block is three times the acceleration for the 1.0-kg block. The acceleration for both blocks are equal. The acceleration is zero, because both blocks are initially at rest. The acceleration for the 1.0 kg block is three times the 3.0 kg block. None of these. A 80.0 kg person climbs a 5.0 m long ladder that leans against a smooth wall and makes an angle of 30 degree with the wall. The mass of the ladder is 20.0 kg. What is the magnitude of the minimum friction force required between the floor and the ladder so that the person can reach the top of the ladder? 113 N 56.6 N 566 N 509 N 453 N

Explanation / Answer

1)

initial verticle velocity = 0

initial horizontal velocity = 30 m/s

verticle acceleration = g = 9.8 m/s^2

horizontal acceleration = 0

final verticle velocity

vy^2 = 0 + 2*9.8*2.7

vy = 7.274 m/s

final horizontal velocity

vx^2 = (30)^2 + 0

vx = 30 m/s

final velocity = sqrt(30^2 + 7.274^2) = 30.87 m/s = 30.9 m/s

2)

acceleration does not depend on mass.

so acceleration for both blocks are same.

3)

answer is (c)

minimum required friction force is 566 N.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.