The effort required to lift a load W on a screw jack with helix angle $$\alpha $$ and angle of friction $$\varphi $$ is equal to
A. $${\text{W}}\tan \left( {\alpha + \varphi } \right)$$
B. $${\text{W}}\tan \left( {\alpha - \varphi } \right)$$
C. $${\text{W}}\cos \left( {\alpha + \varphi } \right)$$
D. $${\text{W}}\sin \left( {\alpha + \varphi } \right)$$
Answer: Option A
This Question Belongs to Civil Engineering >> Strength Of Materials
The weight of a body is due to
A. Centripetal force of earth
B. Gravitational pull exerted by the earth
C. Force of attraction experienced by par-ticles
D. Gravitational force of attraction towards the centre of the earth
The product of either force of couple with the arm of the couple is called
A. Resultant couple
B. Moment of the forces
C. Resulting couple
D. Moment of the couple
A. Density of metal can’t be determined
B. Metal is twice as dense as water
C. Metal will float in water
D. Metal is twice as dense as unknown fluid
Coulomb friction is the friction between
A. Bodies having relative motion
B. Two dry surfaces
C. Two lubricated surfaces
D. Solids and liquids
Join The Discussion