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3 years ago

A dogsled is moving at a constant speed of 3.0 m/s in a straight line on level ground,

Physics

1 answer:

denis-greek [22]3 years ago

6 0

Answer:

0 N

Explanation:

The key for solving the problem is in the sentence "moving at a constant speed in a straight line".

In fact, this means that the velocity of the sled is constant: and therefore, that its acceleration.

Newton's second law states that:

F = ma

where

F is the net force on an object

m is its mass

a is its acceleration

In this problem, we have asserted that the acceleration of the sled is zero:

a = 0

Therefore, according to the equation above, this also means that the net force on the sled is also zero:

F = 0 N

(This implies that there must be another force, must like the force of friction, that acts backward, in the opposite direction to the pull applied by the dogs).

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4 years ago

A student (m = 68 kg) falls freely from rest and strikes the ground. During the collision with the ground, he comes to rest in a

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Answer:

5.7141 m

Explanation:

Here the potential and kinetic energy will balance each other

$mgh=\frac{1}{2}mv^2\\\Rightarrow v=\sqrt{2gh}$

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t = Time taken = 0.04 seconds

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$v=u+at\\\Rightarrow a=\frac{v-u}{t}$

From Newton's second law

$F=ma\\\Rightarrow F=m\frac{v-u}{t}\\\Rightarrow 18000=68\frac{0-\sqrt{2gh}}{0.04}\\\Rightarrow \frac{18000}{68}\times 0.04=-\sqrt{2\times 9.81\times h}\\\Rightarrow 10.58823=-\sqrt{2\times 9.81\times h}$

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