Answer:
The angular acceleration of the wheel is -6.54 rad/s²
Explanation:
We'll use the equations of motion for this.
w = 2πf
f = 75 rpm = 1.25 rps = 1.25 rev/s
w₀ = initial angular velocity = 2π × 1.25 = 7.85 rad/s
w = final angular velocity = 0 rad/s
t = 1.2 s
α = ?
w = w₀ + αt
0 = 7.85 + 1.2α
α = 7.85/1.2 = - 6.54 rad/s²
B) a rock being tossed high into the air
Answer:
Points downward, and its magnitude is 9.8 m/s^2
Explanation:
The motion of a projectile consists of two independent motions:
- A uniform horizontal motion, with constant velocity and zero acceleration. In fact, there are no forces acting on the projectile along the horizontal direction (if we neglect air resistance), so the acceleration along this direction is zero.
- A vertical motion, with constant acceleration g = 9.8 m/s^2 towards the ground (downward), due to the presence of gravity wich "pulls" the projectile downward.
The total acceleration of the projectile is given by the resultant of the horizontal and vertical components of the acceleration. But we said that the horizontal component is zero, therefore the total acceleration corresponds just to its vertical component, therefore it is a vector with magnitude 9.8 m/s^2 which points downward.
cardiac muscle is striated. Uniquely, the cells of this kind of muscle are joined strongly together at adherens junctions that “enable the heart to contract forcefully without ripping the fibers apart.”
Answer:
<em>d. 268 s</em>
Explanation:
<u>Constant Speed Motion</u>
An object is said to travel at constant speed if the ratio of the distance traveled by the time taken is constant.
Expressed in a simple equation, we have:
Where
v = Speed of the object
d = Distance traveled
t = Time taken to travel d.
From the equation above, we can solve for d:
d = v . t
And we can also solve it for t:
Two cars are initially separated by 5 km are approaching each other at relative speeds of 55 km/h and 12 km/h respectively. The total speed at which they are approaching is 55+12 = 67 km/h.
The time it will take for them to meet is:
t = 0.0746 hours
Converting to seconds: 0.0746*3600 = 268.56
The closest answer is d. 268 s
