Answer:
D, using a spring scale to exert a force on the block. Measure the acceleration of the block and the applied force
Explanation:
For this you would use the net force equation acceleration=net force * mass however you will want to isolate mass so it would be acceleration/ net force to get mass. Then process of elimination comes to play.
Not sure but just coming to say good luck and take your time
Answer:
Part a)

Part b)

Part c)

Explanation:
Part a)
As we know that there is no external torque on the system of two twins
so here we will use



Part b)
Since angular momentum is conserved here as there is no external torque
so we will have



Part c)
Work done by both of them = change in kinetic energy
so we have




Answer:
el plomo será el más largo
Explanation:
Dado que;
longitud inicial (l1) = 4m
Longitud final l2
aumento de temperatura (θ) = 10 ° C
Coeficiente de expansión lineal α
Ahora para el hierro;
α = 11,7 x 10-6
Desde;
l2-l / l1θ = α
l2 = α l1θ + l1
l2 = l1 (αθ + 1)
l2 = 4 ((11,7 x 10-6 * 10) + 1)
l2 = 4.00044 m
Para el plomo
l2 = 4 ((27,3 x 10-6 * 10) + 1)
l2 = 4,00109 m
Para cobre
l2 = 4 ((16,7 x 10-6 * 10) + 1)
l2 = 4.000668 m
Por lo tanto, el plomo será el más largo
Answer:
Explanation:
Given
Force 
one at an angle of
East of North and another at
West of North
Net Force is in North Direction

Forces in horizontal direction will cancel out each other
thus Work done will be by north direction forces

here 
