Answer:
a)15 N
b)12.6 N
Explanation:
Given that
Weight of block (wt)= 21 N
μs = 0.80 and μk = 0.60
We know that
Maximum value of static friction given as
Frs = μs m g = μs .wt
by putting the values
Frs= 0.8 x 21 = 16.8 N
Value of kinetic friction
Frk= μk m g = μk .wt
By putting the values
Frk= 0.6 x 21 = 12.6 N
a)
When T = 15 N
Static friction Frs= 16.8 N
Here the value of static friction is more than tension T .It means that block will not move and the value of friction force will be equal to the tension force.
Friction force = 15 N
b)
When T= 35 N
Here value of tension force is more than maximum value of static friction that is why block will move .We know that when body is in motion then kinetic friction will act on the body.so the value of friction force in this case will be 12.6 N
Friction force = 12.6 N
Answer:
6.38 x 10^4 J
Explanation:
d = 0.33 cm = 0.33 x 10^-2 m, Area = 87 x 36 cm^2 = 0.87 x 0.36 m^2
ΔT = 14 degree C, t = 1 min = 60 second
K = 0.8 W / m K
Heat = K A ΔT t / d
H = 0.8 x 0.87 x 0.36 x 14 x 60 / (0.33 x 10^-2)
H = 6.38 x 10^4 J
<span>5. Dry ice is an example of _________, which is the process of a solid turning directly into a gas. (1 point)
sublimation
6. The ____ is a unit of force. (1 point)
</span>n<span>ewton
7. Which of the following is the boiling point of water? (1 point)
100°C
8. Which of the following describes the molecular structure of water at 40°C? (1 point)
water molecules are close together and moving freely around each other </span>
Newtons third law of motion applies to football as when the ball is thrown, force is applied to the football thrown forward and also force back to the player. Therefore it states that every action has a reaction. The player does not get a huge force back from throwing the football due to the player having a bigger mass than the football being thrown.
In short, when the football is throw, there is a reaction with the ball and the player accordingly with the force put into the ball.
