Answer: 
Explanation:
We know that force acting on an object due to Earth's gravity on the surface is given by:

where g is the acceleration due to gravity, r would be radius of Earth, M is the mass of Earth and G is the gravitational constant.
It is given that at pole, g = 9.830 m/s² and r = 6371 km = 6371 × 10³ m



Hence, Earth's mass is 
Horizontal motion is defined as a projectile motion in a horizontal plane depending upon the force acting on it. For a short distance, the vertical and horizontal components of a projectile are perpendicular and independent of each other.
<u>Answer</u>
3.4 s
<u>Explanation</u>
The question can be solve by using the 2nd Newton's law of motion.
s = ut + 1/2at²
Before she is pushed, the initial velocity is zero.
u = 0
Now the equation becomes
s = 0 + 1/2at²
s = 1/2at²
25 = 1/2 × 4.3 × t²
50 = 4.3t²
t² = 50/4.3
= 11.628
t = √11.628
= 3.4 s
Explanation:
It is given that,
Length of solenoid, l = 28 cm = 0.28 m
Area of cross section, A = 0.475 cm² = 4.75 × 10⁻⁵ m²
Current, I = 85 A
(a) The inductance of the solenoid is given by :


L = 0.0000886 H

(b) Energy contained in the coil's magnetic field is given by :


U = 0.3200675 Joules
or
U = 0.321 Joules
Hence, this is the required solution.
Answer:
100km/hr
Explanation:
From the problem statement we know that distance of the trip is 115km
Expected time for the trip = 1.2hrs
→ If she spends the first half-hour going 90km/hr,
Here time = 0.5hr
speed = 90km/hr
The distance covered;
Distance covered = Speed x time
Distance covered = 90 x 0.5 = 45km
→The remaining distance will be:
Total distance - distance covered
115km - 45km = 70km
→ The remaining time;
1.2hr - 0.5hr = 0.7hr
Speed =
Insert the parameters and solve;
Speed =
= 100km/hr
For the remaining lap, the tourist must travel at a rate of 100km/hr to catch up.