Answer:
1. The image of the person is 1.41 m, virtual and formed at the back of the surface of the globe.
2. The person's image is 3.38 m tall.
Explanation:
From the given question, object distance, u = 0.75 m, object height = 1.8 m, radius of curvature of the reflecting globe, r = 8 cm = 0.08 m.
f = 
= 
= 0.04 m
1. The image distance, v, can be determined by applying mirror formula:
= 
+ 
= 
+
- 
=
= 
= - 
⇒ v = -
= - 1.41 m
The image of the person is 1.41 m, virtual and formed at the back of the surface of the globe.
2. 
= 
= 
v = 
= 3.384
v = 3.38 m
The person's image is 3.38 m tall.
Answer:
Explanation:
Given a ball of mass m= 0.5kg
The ball moves in as circle of radius r= 0.4m
Speed of the ball is v = 4m/s
Centripetal force is exerted on ball and it is given as
Fc = m•ac
ac is centripetal acceleration and it is given as
ac = v²/r
Then,
Fc = mv²/r
Fc = 0.5 × 4²/0.4
Fc = 20N.
The force exerted on the ball is 20N
Answer:
Explanation:
This figure given is the frequency; 2 times per second represents frequency.
What is frequency?
- It is the number of times per seconds something goes past or around another.
it is expressed as:
Frequency = 
where n is the number of turns
t is the time taken
Therefore, the Barber spinned him 2 times in 1 second.
The period is the inverse of frequency. It is the time taken for a body to go through a point;
Period = 
= 
s
Answer:
v= s/t
Explanation:
250 km/ h =69.44m/s
S1=2 times 69.44 ≈ 139m
Next 2.5 seconds:
S2 = 100m
Average speed:
v=139m+100m/2s+2.5s = 239/4.5s = 53.2 m/s=192km/h
