HOME > > Can someone explain a couple physics problems involving Newton's laws
Can someone explain a couple physics problems involving Newton's laws
[From: ][author: ][Date: 12-03-16][Hit: ]
81m/s^2, then the weight has a mass of 44.1/9.81 =~ 4.49kg.Its stationary,......
T*sin 85 = 80*g and T*cos 85 = 80*a; squaringand addinggives
T^2 = (80^2)(g^2 + a^2) or
T = 80*sq rt[g^2 +a^2] --------------- 1
Also a/g = cot 85 or a = g*cot 85 giving a = 9.81*cot 85 = 0.858 or 0.86 m/s^2
From 1 we have
T = 80*9.81*cosec 85 = 787.79 or 787.8 N
-
First one:
The question doesn't say what the local gravity is, so you can't tell.
But assuming "standard gravity" of 9.81m/s^2, then the weight has a mass of 44.1/9.81 =~ 4.49kg.
It's stationary, so the forces on it balance - 44.1N of weight downards, and 44.1N of pull upwards from the spring
For the weight to accelerate downwards at 3m/s^2, there must be an unbalanced force on it (from F=ma) of
about 13.5N. It still has the same weight - 44.1N downwards - so the upwards pull from the spring must be less.To get the scale reading, subtract 13.5 from the original 44.1N giving about 30.6N
2nd one - the centripetal force comes from the friction of the tires on the track
