Question 1 A motorcycle has a mass 250 kg. This motorcycle makes a turn with a r

Question

Question 1 A motorcycle has a mass 250 kg. This motorcycle makes a turn with a radius of 13.7 m at a speed of 96.5 km/h. What is the centripetal force on the motorcycle? 1. 719 N 2. 2.95 x 103N 3. 1.31 x 104N 4. 4.31 x 104N

Question 2 The acceleration of gravity on the Moon is one-sixth what it is on Earth. An object of mass 72 kg is taken to the Moon. What is its mass there? 1. 12 kg 2. 72 kg 3. 72 N 4. 12 N

Question 3 A person pulls a 10-kg crate 20 meters across the floor using a force of 40 N at an angle of 30o above floor. How much work is done by the person? 1. 400 J 2. 690 J 3. 800 J 4. 1960 J

Question 4

A basketball of mass 0.60 kg hits the floor with a downward velocity of 4.0 m/s. Immediately after contact with the floor, the ball bounces upwards with an initial speed of 3.0 m/s. The time of contact between the ball and the floor is 0.01 s. What is the average force which the floor exerts on the ball during this collision? 1. 60 N 2. 180 N 3. 300 N 4. 420 N

question 5

A 90 kg football player moving at 8.0 meters per second tackles a 100 kg player moving at 5.0 meters per second in the opposite direction. What is the velocity of the two players immediately after the tackle (before they hit the ground)? 1. 0.0 m/s 2. 1.2 m/s 3. 3.0 m/s 4. 6.4 m/s

Explanation / Answer

Question 1

speed = v = 96.5 km / h = 96.5 * 5 / 18 m/sec = 26.805556 m/sec

so centripetal force = mass * v^2 / radius = 250 * 26.805556^2 / 13.7 = 13,112 = 1.31 * 10^4 N .... option 3

Question 2

the mass of the object will remain same as mass is an intrinsic property... so mass = 72 kg ... option 3

Question 3

force applied = 40 N

displacement = 20 m

angle = 30 degree

work = force * discplacement * cos( angle ) = 40 * 20 * cos 30 = 692.82 J ..... option 2

Quesion 4

intiial momentum = mass * velocty = 0.6 * 4 = 2.4

final momentum = 0.6 * ( -3 ) = -1.8

so change in momentum = -1.8 - 2.4 = -4.2

force = change in momentum / time = -4.2 / 0.01 = - 420 N .... option 4

Question 5

In tackling , both the players will move with the same speed after collisoin ..

so Let this combined velocity after collsion be v...

intial momentum = 90 * 8 - 100 * 5 = 220

final momentum = (90+100) * v = 190 v

conserving momentum ..

final = intial

190 v = 220

v = 1.158 m/sec ....option 2

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