Related Questions

By walking at 3/4 of his usual speed, a man reaches his office 20 minutes later than usual. His usual time is :
A 30 minutes
B 75 minutes
C 45 minutes
D 60 minutes
The usual value of the point angle of a drill is
A 70°
B 100°
C 118°
D 130°
The helix angle of a drill is __________ for drilling brass.
A Equal to 30°
B Less than 30°
C More than 30°
D None of these
A person walking 5/6 of his usual rate is 40 minutes late. What is his usual time?
A 2 hours 20 minutes
B 3 hours 20 minutes
C 2 hours
D 4 hours 10 minutes
A train left 1 hour later than the scheduled time but in order to reach its destination 200 km away in time, it had to increase its usual speed by 10 km/hr. What is the usual speed (in km/hr) of the train?
A 38
B 42
C 45
D 40
Travelling at 4/5th of his usual speed, a man is 15 minutes late. What is his usual time to cover the same distance?
A 15 min
B 1 hr
C 75 min
D 45 min
In order to ensure self locking in a screw jack, it is essential that helix angle is __________ friction angle.
A Larger than
B Smaller than
C Equal to
D None of these
In a screw jack, the effort required to lift the load W is given by (where $$\alpha $$ = Helix angle and $$\varphi $$ = Angle of friction)
A $${\text{P}} = {\text{W}}\tan \left( {\alpha - \varphi } \right)$$
B $${\text{P}} = {\text{W}}\tan \left( {\alpha + \varphi } \right)$$
C $${\text{P}} = {\text{W}}\tan \left( {\varphi - \alpha } \right)$$
D $${\text{P}} = {\text{W}}\cos \left( {\alpha + \varphi } \right)$$
The efficiency of a screw jack is maximum, when (where $$\alpha $$ = Helix angle and $$\varphi $$ = Angle of friction)
A $$\alpha = {45^ \circ } + \frac{\varphi }{2}$$
B $$\alpha = {45^ \circ } - \frac{\varphi }{2}$$
C $$\alpha = {90^ \circ } + \varphi $$
D $$\alpha = {90^ \circ } - \varphi $$
The efficiency of a screw jack is maximum, when (where $$\alpha $$ = Helix angle and $$\varphi $$ = Angle of friction.)
A $$\alpha = {45^ \circ } + \frac{\varphi }{2}$$
B $$\alpha = {45^ \circ } - \frac{\varphi }{2}$$
C $$\alpha = {90^ \circ } + \varphi $$
D $$\alpha = {90^ \circ } - \varphi $$

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