Answer:
A. 2.8 m/s
Explanation:
Suppose that at the height of 0 m, the path of the pendulum is lowest.
If we use law of conservation of energy, the pendulum will have zero kinetic energy or K.E when it is at highest point, because K.E happens during movement of object and at the highest point all the energy will be P.E
P.E= mgh
Similarly, when the pendulum reaches at the lowest point, the height becomes zero and the P.E also becomes zero. Now all the energy will be K.E
K.E= 1/2 m v^2
In question, we are asked about the speed as the pendulum it reaches the lowest point of its path. Like we mentioned P.E will be zero at lowest point because of zero height. And also we will use law of conservation of energy because no energy has been lost from system.
K.E= P.E
1/2 m v^2 = mgh
Taking sq.root at both sides
v= Under root 2 gh
v=Under root 2x 9.8 m/s x0.4 m
v=Under root 7.84
v=2.8 m/sec
Hope it helps!
Answer:
B.)Angular momentum is always conserved
Explanation:
Angular momentum is given by:
where
m is the mass of the object
v is its speed
r is the distance between the object and the centre of its circular trajectory
In absence of external torques, angular momentum is always conserved. That means that for the spinning star, if its radius r decreases (because it shrinks), in order for L (the angular momentum) to be conserved, the speed (v) must increases, therefore the spinning star speeds up.
So, the correct choice is
B.)Angular momentum is always conserved
Toy car will take the least amount of force.
this is because the toy car has a much lighter mad than the other objects meaning it will take less force to get it to move.
Ok so we know:
The acceleration (10ms^-2)
The initial velocity (0)
And the total time (6seconds)
Using the equation v = u + at, with v being the final velocity, u being the initial velocity, a being acceleration and t being time, we get:
v = 0 + 10x6
v = 60
So the speed after 6 seconds is 60 metres per second (6m/s)
Hope this helped
