A pendulum is 0.9 m long and the bob has a mass of 1.0 kg. At the bottom of its swing, the bob's speed is 1.6 m/s. What is the tension in the string at the bottom of the swing

Wouldn't tension be weight+ centripetalforce?

To find the tension in the string at the bottom of the swing, we need to consider the forces acting on the bob. At the bottom of the swing, two forces are acting on the bob: the tension force from the string and the gravitational force.

We can use the equation for centripetal acceleration to find the net force acting on the bob:
F_net = m * a
where F_net is the net force, m is the mass of the bob, and a is the centripetal acceleration.

In this case, the centripetal acceleration is equal to the acceleration due to gravity (g). So we have:
F_net = m * g

The net force is equal to the tension force minus the gravitational force:
F_net = T - m * g

Now, we need to find the gravitational force acting on the bob. The gravitational force can be calculated as the product of the mass of the bob (m) and the acceleration due to gravity (g):
F_gravity = m * g

Substituting the value of F_gravity into the first equation, we have:
T - m * g = m * g

Now, we can isolate T, the tension force:
T = 2 * m * g

Given that the mass of the bob (m) is 1.0 kg, and the acceleration due to gravity (g) is approximately 9.8 m/s^2, we can plug in these values to find the tension force:
T = 2 * 1.0 kg * 9.8 m/s^2
T = 19.6 N

Therefore, the tension in the string at the bottom of the swing is 19.6 Newtons.