As per the question the mass of the boy is 50 kg.
The boy sits on a chair.
We are asked to calculate the force exerted by the boy on the chair at sea level.
The force exerted by boy on the chair while sitting on it is nothing else except the force of gravity of earth i.e the weight of the body .The direction of that force is vertically downward.
At sea level the acceleration due to gravity g = 9.8 m/s^2
Hence the weight of the boy 
[m is the mass of the body]
we have m = 50 kg.
Hence w = 50 kg ×9.8 m/s^2
=490 N kg m/s^2
= 490 N
Here newton [N] is the unit of force.
Answer:
Explanation:
we know angular velocity in terms of moment of inertia and angular speed
ω .... (1)
moment of inertia of rod rotating about its center of length b
........ .(2)
using v = ωr
where w is angular velocity
and r is radius of rod which is equal to b
so we get 2v = ωb
ω = 2v/b ................. (3)
here velocity is two time because two opposite ends are moving opposite with a velocity v so net velocity will be 2v
put second and third equation in ist equation
×
so final answer will be 
Answer:
Explanation:
As we know that the angular acceleration of the wheel due to friction is constant
so we can use kinematics
so we have
now time required to completely stop the wheel is given as
now time required to stop the wheel is given as
We can make pretty good guesses for their masses, but kinetic energy also depends on their speeds, which we don't know, and may change.
As an example ... If the truck, the van, the car, and the bike are all parked at the mall, then a scampering mouse has more kinetic energy than all of them combined.
As the question stands, no answer is possible.
1. True
2. True
3. True
4. True
5. 10ft
