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Unless you need to edit, it's safer to stay in Protected View. Enable Editing Newton- A block starts from rest and slides down an inclined plane 1.2 meters long that is at an angle of 5 degrees. The coefficient of sliding friction is 0.05. What is the acceleration of the block down the plane due to gravity? a) 9.76 m/s2 b) 0.85 m/s c) 0.37 m/s d) 1.34 m/s e) 0.49 m/s 6. 7. Work: A car with a mass of 1000 kg moving at 21 m/s come to a stop in a distance of 3 meters in a collision with a crash barrier. What is the average force on the car by the crash barrier? a) 73500 N b) 220500 N c) 7000 N d) 21000 N e) there is no way to tell without knowing the time of the collision 8. Energy Conservation: A block on a frictionless surface starts at a height of 2 meters above the floor and slides down a ramp 6 meters long. What is the velocity of the block when it is 1.5 meters above floor level? a) 5.4 m/s b) 3.1 m/s c) 6.3 m/s d) 2.0 m/s e) 3.27 m/s 9. Circular motion: A record turntable 15 cm in radius rotates at a constant 33.3 rpm. Find the angular speed in radians per second of the turntable and the velocity in m/s of a point on its rim. a) 5.3 rad/s and 0.79 m/s b) 209 rad/s and 31.4 m/s c) 3.49 rad/s and 0.52 m/s d) 318 rad/s and 47.7 m/s e) 0.56 rad/s and 0.083 m/s t e

Explanation / Answer

6. Net force on object

ma= mg sin x - u mg cos x

a= 9.8( sin 5 - 0.05* cos 5)

= 0.37 m/s^2

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7.

acceleration of the car

a= v^2/(2d)= 21^2/(2* 3)

a= 73.5 m/s^2

Force= ma= 10000* 73.5= 73500 N

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8. Using conservation of energy

Total potential energy at top= kinetic energy at given point+ potential energy at given point

mgH= mgh+ 0.5 mv^2

9.8*( 2-1.5)= 0.5* v^2

v= 3.1 m/s

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9. Angular speed

w= ( 2*pi/60)* 33.33= 3.49 rad/s

Option (c ) is correct.

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Comment in case any doubt.. good luck

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