Answer:
- Distance between car and the deer when the car stopped = 20 m
- The time required for you to stop once you press the brakes = less than 5 s in order not to hit the deer.
Explanation:
Using the equations of motion,
In the 0.5 s reaction time, we need to first calculate how far he has travelled in that time.
a = 0 m/s² (Since the car is travelling at constant velocity)
x = ?
Initial velocity = u = 20 m/s
x = ut + at²/2
x = 20×0.5 + 0 = 10 m
From that moment,
a = - 10 m/s²
u = initial velocity at the start of the deceleration = 10 m/s
v = final velocity = 0 m/s
x = ?
v² = u² + 2ax
0² = 10² + 2(-10)(x)
20x = 100
x = 5 m
Total distance travelled from when the deer stepped onto the road = 10 + 5 = 15 m
Distance between car and the deer when the car stopped = 35 - 15 = 20 m
b) To determine the time required to stop once you step on the brakes
u = 10 m/s
t = ?
v = 0 m/s²
x = distance from when the brake was stepped on to the deer = 35 - 10 = 25 m
x = (u + v)t/2
25 = (10 + 0)t/2
10t = 50
t = 5 s
Meaning the time required to stop once you step on the brakes is less than 5s.
Answer:
a. 0.21 rad/s2
b. 2.205 N
Explanation:
We convert from rpm to rad/s knowing that each revolution has 2π radians and each minute is 60 seconds
200 rpm = 200 * 2π / 60 = 21 rad/s
180 rpm = 180 * 2π / 60 = 18.85 rad/s
r = d/2 = 30cm / 2 = 15 cm = 0.15 m
a)So if the angular speed decreases steadily (at a constant rate) from 21 rad/s to 18.85 rad/s within 10s then the angular acceleration is
b) Assume the grind stone is a solid disk, its moment of inertia is
Where m = 28 kg is the disk mass and R = 0.15 m is the radius of the disk.
So the friction torque is
The friction force is
Since the friction coefficient is 0.2, we can calculate the normal force that is used to press the knife against the stone
Answer:
False
Explanation:
Convection currents do not produce heat. In fact, convection current are a method of transfer of heat, not of production. Convection occurs when there is a fluid which is heated from bottom, from an external source of heat (such as a pot of boiling water over a flame): the bottom part of the fluid becomes warmer, and so less dense than the colder part, therefore it starts moving up, and it is replaced by the colder parts of the fluid, which go down. Later, these colder parts become warmer, so they start going up, being replaced by new colder parts, etc... in a cycle. This is known as convection current, but it requires an external source of heat, it does not produce heat by itself.
Answer:
28.7%
Explanation:
efficiency = work output /work input × 100
A) nucleus because some aims reflected off the gold foil proving that there was something bigger inside the atom hence discovering the nucleus
