Third Law of Newton

 A student weighing 600 N stands on a spring scale in an elevator. If the scale reads 800 N, the elevator must be     

• moving downward at constant speed
• accelerating upward
•  accelerating downward          
• moving upward at constant speed   

A student puts a box weighing 50 N on a spring scale in an elevator. If the scale reads 20 N, the elevator must be.       

• moving upward at constant speed
• accelerating upward
•  accelerating downward
• moving downward at constant speed

 A student weighing 600 N stands on a spring scale in an elevator. If the scale reads 400 N, the elevator must be      

• moving downward at constant speed
•  moving upward at constant speed
•  accelerating upward 
• accelerating downward 

A student weighing 350 N stands on a spring scale in an elevator. If the scale reads 200 N, the elevator must be        

• accelerating downward
• accelerating upward 
•  moving upward at constant speed
• moving downward at constant speed

1.      A woman standing on a scale in an elevator notices that the scale reads 20 N greater than her normal weight. Which type of movement on the part of the elevator could cause this greater than normal reading? 

• accelerating downward 
• moving upward at constant speed
• moving downward at constant speed 
• accelerating upward

1.      A woman standing on a scale in an elevator notices that the scale reads 20 N less than her normal weight. Which type of movement on the part of the elevator could cause this lesser than normal reading?

• accelerating downward
• moving upward at constant speed
• moving downward at constant speed 
• accelerating upward

1.       A person of mass 94 kg is standing in a lift which is accelerating upwards at 0.54 m/s² .calculate the force, F, the person exerts on the floor of the lift. 

• 1706 N
• 497 N
• 174 N
• 51 N