As a simple pendulum of length ℓ sweeps back and forth in the arc of a circle, there are two forces acting on it: gravity m g an
d the force T exerted by the supporting string. As the pendulum swings, its speed and velocity continually change, meaning work is being done on it. Which force(s) do work?
1 answer:
Answer:
Gravity
Explanation:
Lets take the mass of the pendulum = m
Angle from vertical axis = θ
From the diagram
The gravity force mg have two component ,First one mg cosθ and other one is mg sinθ.
The component of gravity force mg sinθ is responsible for the motion of the pendulum ,that is why gravity does work in the pendulum.
Therefore the answer is -
Gravity
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Answer:
<em>The mass of the apple is 0.172 kg (172 g)</em>
Explanation:
<u>The Law Of Conservation Of Linear Momentum </u>
The total momentum of a system of bodies is conserved unless an external force is applied to it. The formula for the momentum of a body with mass m and speed v is
P=mv.
If we have a system of two bodies, then the total momentum is the sum of both momentums:
If a collision occurs and the velocities change to v', the final momentum is:
Since the total momentum is conserved, then:
P = P'
Or, equivalently:
If both masses stick together after the collision at a common speed v', then:
We are given the mass of an arrow m1=43 g = 0.043 kg traveling at v1=84 m/s to the right (positive direction). It strikes an apple of unknown mass m2 originally at rest (v2=0). The common speed after they collide is v'=16.8 m/s.
We need to solve the last equation for m2:
Factoring m2 and m1:
Solving:
Substituting:
The mass of the apple is 0.172 kg (172 g)
The position of the mass is given by (in cm):
The velocity is the derivative of the position:
Substituting t=0.40 s, we can find the velocity at this time:
The velocity is the derivative of the position:
Substituting t=0.40 s, we can find the velocity at this time: