JAMB Physics Past Questions & Answers - Page 256

1,276.

An elevator of mass 4800kg is supported by a cable which can safely withstand a maximum tension of 60 000N. The maximum upward acceleration the elevator can have is

A.

2.5ms-2

B.

5.0ms-2

C.

7.5ms-2

D.

10.0ms-2

Correct answer is A

a = \(\frac{F}{m}\)

= \(\frac{60000 -(4800 \times10)}{4800}\)

= 2.5ms-2

1,277.

A man walks 8km north and then 5km in a direction 60o east of north. Find the distance from his starting point

A.

11.36km

B.

12.36km

C.

13.00km

D.

14.36km

Correct answer is A

R = \(\sqrt {5^2 + 8^2 - 2 \times 5 \times 8 \times cos 120^o}\)

R = \(\sqrt{129}\)

= 11.36km

1,278.

A jet engine develops a thrust of 270Ns when the velocity of the exhaust gases relative to the engine is 300ms-1. What is the mass of the material ejected per second?

A.

81.00kg

B.

9.00kg

C.

0.90kg

D.

0.09kg

Correct answer is C

Thrust = force x time

thrust = \(\frac{m(v - u)}{t}\) x \(\frac{t}{1}\)

270 = m(300 - 0)

m = 0.90kg

1,279.

Which of the following units is equivalent to kgms-1?

A.

Ns-1

B.

Nms-1

C.

Ns

D.

Js-1

Correct answer is C

kgms-1 = \(\frac{mass}{distance}\)

since, F = ma = kgms-1 = N

kgms-1 = Ns

1,280.

Which of the following symbolic representations is correct for an atom X with 22 electrons and 43 neutrons?

A.

\(^{43}_{22}X\)

B.

\(^{22}_{43}X\)

C.

\(^{65}_{43}X\)

D.

\(^{65}_{22}X\)

Correct answer is D

No explanation has been provided for this answer.