Answer:
It allows you to walk faster.
Explanation:
It is the same force that allows you to accelerate forward when you run. Your planted foot can grip the ground and push backward, which causes the ground to push forward on your foot. We call this grip type of friction, where the surfaces are prevented from slipping across each other, a static frictional force.
Answer:
Heat energy required (Q) = 3,000 J
Explanation:
Find:
Mass of water (M) = 200 g
Change in temperature (ΔT) = 15°C
Specific heat of water (C) = 1 cal/g°C
Find:
Heat energy required (Q) = ?
Computation:
Q = M × ΔT × C
Heat energy required (Q) = Mass of water (M) × Change in temperature (ΔT) × Specific heat of water (C)
Heat energy required (Q) = 200 g × 15°C × 1 cal/g°C
Heat energy required (Q) = 3,000 J
Answer:
A. 1.4 m/s to the left
Explanation:
To solve this problem we must use the principle of conservation of momentum. Let's define the velocity signs according to the direction, if the velocity is to the right, a positive sign will be introduced into the equation, if the velocity is to the left, a negative sign will be introduced into the equation. Two moments will be analyzed in this equation. The moment before the collision and the moment after the collision. The moment before the collision is taken to the left of the equation and the moment after the collision to the right, so we have:

where:
M = momentum [kg*m/s]
M = m*v
where:
m = mass [kg]
v = velocity [m/s]

where:
m1 = mass of the basketball = 0.5 [kg]
v1 = velocity of the basketball before the collision = 5 [m/s]
m2 = mass of the tennis ball = 0.05 [kg]
v2 = velocity of the tennis ball before the collision = - 30 [m/s]
v3 = velocity of the basketball after the collision [m/s]
v4 = velocity of the tennis ball after the collision = 34 [m/s]
Now replacing and solving:
(0.5*5) - (0.05*30) = (0.5*v3) + (0.05*34)
1 - (0.05*34) = 0.5*v3
- 0.7 = 0.5*v
v = - 1.4 [m/s]
The negative sign means that the movement is towards left