Physics
A man stands in a lift which accelerates upwards. The resultant reaction force on the floor of the lift is
Greater than the weight of the man
Less than the weight of the man
Same as the weight of the man
Zero
Greater than the weight of the man
The weight of the man mg is acting on the floor. As the lift is moving up with an acceleration, say a, the man too in it is having this acceleration. The force producing this acceleration is ma. By Newton’s third law, this force will have an equal reaction pressing the floor equal to ma. Therefore the total resultant reaction on the floor is mg+ma = m(g+a) which is mg, the weight of the man. So (a) is correct.
Greater than the weight of the man The weight of the man mg is acting on the floor. As the lift is moving up with an acceleration, say a, the man too in it is having this acceleration. The force producing this acceleration is ma. By Newton’s third law, this force will have an equal reaction pressing the floor equal to ma. Therefore the total resultant reaction on the floor is mg+ma = m(g+a) which is mg, the weight of the man. So (a) is correct.
Related posts
Radian is used to measureA. Temperature
B. Intensity of Flame
C. Angle
D. Solid Angle
Flemings ”Left hand Rule” is associated with the effect of
A. Electric field on current
B. Magnetic field on magnet
C. Electric field on magnet
D. Magnetic Field on current
The sky appears blue due to
A. Rayleigh scattering
B. Mie scattering
C. Back scattering
D. None of the above
Vehicles use ________ to see the objects coming from behind.
A. Concave lens
B. Convex lens
C. Convex mirror
D. Concave mirror
Which elements are malleable and good conductors of electricity?
A. Tin and silver
B. Iodine and silver
C. Tin and xenon
D. Iodine and xenon
The colour of the ocean appears to be blue because the sunlight falling on it is
A. Reflected
B. Refracted
C. Diffracted
D. Scattered
Mach number is used in connection with the speed of
A. sound
B. aircraft
C. spacecraft
D. ships
Leave a Reply