Explanation:
It is given that,
Diameter of the semicircle, d = 45 m
Radius of the semicircle, r = 22.5 m
Speed of greyhound, v = 15 m/s
The greyhound is moving under the action of centripetal acceleration. Its formula is given by :



We know that, 


Hence, this is the required solution.
Answer:
860.6 years.
Explanation:
The parameters given are;
Initial detector activity = 370000 alpha decays per second
Final detector activity = 93000 alpha decays per second
Formula for time to change in activity is given by the following relation;

t₉₃₀₀₀ = 2.72 × 10¹⁰ seconds = 860.6 years.
Answer:
Yes
Explanation:
Kinetic energy is K.E1/2mv2 so that means it is directly proportional to mass and velocity.
Answer:
D. Half as great
Explanation:
Since we know that the friction force between the surface of crate and ground is given as

so here we know that
= friction coefficient between two surfaces which depends on the effective contact area between two surfaces
= normal force due to the object
So when we turn the object on another side such that the surface area is half then the friction coefficient will become also half
So here the friction force will also reduce to half
so correct answer will be
D. Half as great