A girl is sitting in a sled sliding horizontally along some snow (there is friction present).
1 answer:
Answer:
159 N
Explanation:
There are two types of force of friction:
- Static friction: this is the force of friction that occurs when the object is at rest
- Kinetic friction: this is the force of friction that occurs when the object is in motion
In this problem, the girl is sitting on the sled, and the sled is sliding: this means that the object is in motion, therefore the force of friction that we have to calculate in this problem is the force of kinetic friction.
The force of kinetic friction acting on an object sliding over a flat surface is given by
where
is the coefficient of kinetic friction
N is the normal force on the object
In this problem:
N = 636 N
Therefore, the force of kinetic friction is
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Answer:
10.93m/s with the assumption that the water in the lake is still (the water has a speed of zero)
Explanation:
The velocity of the fish relative to the water when it hits the water surface is equal to the resultant velocity between the fish and the water when it hits it.
The fish drops on the water surface vertically with a vertical velocity v. Nothing was said about the velocity of the water, hence we can safely assume that the velocity if the water in the lake is zero, meaning that it is still. Therefore the relative velocity becomes equal to the velocity v with which the fish strikes the water surface.
We use the first equation of motion for a free-falling body to obtain v as follows;
v = u + gt....................(1)
where g is acceleration due to gravity taken as 9.8m/s/s
It should also be noted that the horizontal and vertical components of the motion are independent of each other, hence we take u = 0 as the fish falls vertically.
To obtain t, we use the second equation of motion as stated;
Given; h = 6.10m.
since u = 0 for the vertical motion; equation (2) can be written as follows;
substituting;
Putting this value of t in equation (1) we obtain the following;
v = 0 + 9.8*1.12
v = 10.93m/s
Answer:
1. 18.25 m/s
2. 0 m/s
Explanation:
1.So the centripetal acceleration of the ball at this lowest point must be, taking gravity into account
The speed at this point would then be
2. Similarly, if T = mg, then the centripetal acceleration must be
As the ball has no centripetal acceleration, its speed must also be 0 as well.