JAMB - Physics (1987 - No. 7)
The coefficient of static friction between a 40kg crate and concrete surface is 0.25. Find the magnitude of the minimum force needed to keep the crate stationary on the concrete base inclined at 45o to the horizontal. [G = 10ms-1]
400N
300N
283N
212N
Giải thích
momentum force = Rsin\(\theta\) - \(\mu\)Rcos\(\theta\)
Fm = (40 x 10 x sin 45) - (40 x 10 x 0.25 x cos 45)
= 212N
Fm = (40 x 10 x sin 45) - (40 x 10 x 0.25 x cos 45)
= 212N