List of practice Questions

A man of mass 70 \(\text {kg}\) stands on a weighing scale in a lift which is moving 

1. upwards with a uniform speed of 10 \(\text m \,\text s^{-1}\) , 
2. downwards with a uniform acceleration of 5 \(\text m \,\text s^{-2}\) , 
3. upwards with a uniform acceleration of 5 \(\text m \,\text s^{-2}\) . What would be the readings on the scale in each case? 
4. What would be the reading if the lift mechanism failed and it hurtled down freely under gravity ?

A stone of mass 0.25 kg tied to the end of a string is whirled round in a circle of radius 1.5 m with a speed of 40 rev./min in a horizontal plane. If, the speed of the stone is increased beyond the maximum permissible value, and the string breaks suddenly, which of the following correctly describes the trajectory of the stone after the string breaks -

A body of mass 5 kg is acted upon by two perpendicular forces 8 N and 6 N. Give the magnitude and direction of the acceleration of the body.