Answer:
options A and C
Explanation:
Since, the spheres are of same size and rotational speed of the sphere are not dependent on their masses. So, both the sphere will reach the bottom of the at the same time with the same speed. But their kinetic energies are different.
So, options A and C are correct.
Answer:
The value is
Explanation:
From the question we are that
The velocity 
The time taken is
The total mass of the train is 
Generally the average power delivered is mathematically represented as
=>
=>
Answer:
87.1 mph
Explanation:
We are given that
Mass,m=60 kg
Power,P=340 W
Speed,v=5 m/s
Area,
Drag coefficient,
Coefficient of rolling resistance,
Friction force,
Where 
Let speed of cyclist=v'
Drag force,
Density of air,

Power,P=



1 m=0.00062137 miles
1 hour=3600 s
FOUR USES OF CONCAVE MIRROR:Satellite dishes,headlights of a car, telescopes used for astronomical studies, and shaving mirrors because of there curved and reflective surface.
FIVE USES OF LENSES: Camera lens ,microscopes ,magnifying glass,eyeglasses,projector
Answer:
42.0×10² second²
Explanation:
Here, time is given in milisecond
(64800 ms)²
= 4199040000 ms²
The SI unit is seconds
1 second = 1000 milisecond



42.0×10² second²