- #1
Kennedy
- 70
- 2
A mass m = 0.15 kg is attached to a massless string and rotates at constant speed v = 4 m/s in a horizontal circle of radius 2 m. The tension T (in N) in the string is: (a) 1.1 (b) 1.9 (c) 2.4 (d) 3.3 (e) 4.9
I would assume that first I calculate the centripetal acceleration by using v^2/r = a. That gives me 0.8 m/s^2. Since the mass is moving in a horizontal circle, there should be no extra tension at the bottom due to the force of gravity, so I would assume that the tension in the string is simply 0.8(0.15) which is 1.2 N, but my answer key tells me that the answer is 1.9 N, which doesn't make any sense to me. Can someone guide me through this?
I would assume that first I calculate the centripetal acceleration by using v^2/r = a. That gives me 0.8 m/s^2. Since the mass is moving in a horizontal circle, there should be no extra tension at the bottom due to the force of gravity, so I would assume that the tension in the string is simply 0.8(0.15) which is 1.2 N, but my answer key tells me that the answer is 1.9 N, which doesn't make any sense to me. Can someone guide me through this?