Answer:
Fr = 48 [N] forward.
Explanation:
Suppose the movement is on the X axis, in this way we have the force of the engine that produces the movement to the right, while the force produced by the brake causes the vehicle to decrease its speed in this way the sign must be negative.
∑F = Fr
![F_{engine}-F_{brake} =F_{r}\\F_{r}=79-31\\F_{r}=48[N]](https://tex.z-dn.net/?f=F_%7Bengine%7D-F_%7Bbrake%7D%20%3DF_%7Br%7D%5C%5CF_%7Br%7D%3D79-31%5C%5CF_%7Br%7D%3D48%5BN%5D)
The movement remains forward, since the force produced by the movement is greater than the braking force.
Answer:
AFter 3.5 s, the wagon is moving at: 
Explanation:
Let's start by finding first the net force on the wagon, and from there the wagon's acceleration (using Newton's 2nd Law):
Net force = 250 N + 178 N = 428 N
Therefore, the acceleration from Newton's 2nd Law is:
So now we apply this acceleration to the kinematic expression for velocity in an object moving under constant acceleration:
Answer:
The answer is below
Explanation:
The average resistivity of the human body (apart from surface resistance of the skin) is about 5.0 Ωm. The conducting path between the right and left hands can be approximated as cylinder 1.6 m long and 0.10 m in diameter. The skin resistance can be made negligible by soaking the hands in salt water. (a) What is the resistance between the hands if the skin resistance is negligible? (b) if skin resistance is negligible, what potential difference between the hands is needed for lethal shock current 100 mA?
Solution:
The resistance (R) of a material is given by the formula:
R = ρL / A
where L is the length of the conductor, ρ is resistivity and A is the cross sectional area.
a) R = ρL / A
ρ = 5.0 Ωm, L = 1.6 m, A = π(diameter²) / 4 = π(0.1²)/4 = 0.00785 m²
R = 5(1.6) / 0.00785 = 1018.6 ohm
b) To produce 100 mA, we need to use ohms law:
I = 100 mA = 0.1 A, R = 1018.6 ohm
V = IR = 0.1(1018.6)
V = 101.86 V
Answer:
General perception: Physics is harder than Mathematics. Why? Physics might be more challenging because of the theoretical concepts, the mathematical calculations, laboratory experiments and even the need to write lab reports.
Explanation:
